UNIVERSITY  OF  CALIFORNIA 
AT   LOS  ANGELES 


GIFT  OF 


Analysis  of  White  Paints 


A  COLLECTION  OF  NOTES  ON 

THE  CHEMICAL  ANALYSIS 

OF  WHITE  AND  TINTED  PAINTS 


George  H.  Ellis,  B.  Sc. 

ANALYTICAL  CHEMIST  AND  ASSAYER 

.  .  .  Late  Chemist .  .  . 

Chicago,  Burlington  &  Quincy  R'y  Co. 


The  Technical  Press,  Evanston,  III. 


Copyrighted  by 

GEORGE  H.  ELLIS 

1898 


TP 
936 


PREFACE. 

E  following-  pages  appeared  originally  in  the  columns 
of  the  "Paint,  Oil  and  Drug-  Review,"  and  they  are 
now  offered  in  book  form  at  the  request  of  chemists  and 
v     many  others  in  the  paint  trade. 

V 

While  there  has  been  much  literature  published  in  the 

^     technical  and  trade  journals,  yet  there  is  no  volumn  which 

treats  solely  of  the  chemical  analysis  of  paints,  and  it  is 

v     hoped    that   this   little    book    may    at   least    partially    fill 

the  place. 

The  author  wishes  to  here  express  his  obligations  for 

C     valuable  advice  and  the  many  suggestions  offered  by  Mr. 

;     Walter  Lee  Brown,  Prof.  J.  H.  Long,  Mr.  Roger  S.  Pitkin, 

X     and  particularly  to  Prof.  Vernan  J.  Hall  for  his  careful 

*v^  revision  of  proof.  G.  H.  E. 


Chemical  Laboratory, 
May,  1899. 


2G2460 


CONTENTS. 
INTRODUCTORY   REMARKS. 


CHAPTER  I. 

TAG* 


Preparing-  samples  for  analysis 


CHAPTER  II. 
White  Pigments. 

1.  Calcium  Carbonate  ............................................  7 

2.  Gypsum  .....................................................  10 

3.  China  Clay  ...................................................  10 

4.  Silica  .........................................................  15 

5.  Barium  Sulphate  .............................................  16 

6.  Magnesium  Carbonate..   .....................................  17 

7.  Magnesium  Silicate  ....................................  ......  18 

8.  Zinc  Oxide  ..................................................  19 

9.  White  Lead  ...........................  .................    ......  24 


CHAPTER  EL 
White  and  Tinted  Paints. 

1.  Qualitative  analysis  of  White  or  Tinted  Paints,  Paste  Paints, 

Fillers  and  Enamel  Paints  ...............................  31 

2.  Quantitative    analysis    of     White    or    Tinted    Paints,  Paste 

Paints,  Fillers  and  Enamel  Paints.    Scheme  1  ............  38 

Scheme  II  ...........  44 

4.  Analyses  of  "  Ready  Mixed  Paints  "  .........................  47 

5.  Analyses  of  White  Paste  Paints  ............  .................  48 

APPENDIX. 

1.  Estimation  of  Turpentine,  Benzine  and  Water  ................  49 

2.  Estimation  of  Linseed  Oil  in  Flax  Seed  and  Oil  Cake  .........  52 

3.  List  of  the  Principal  Pigments,  with  Chemical  Formulae  and 

Trade  Names  ............................................  54 

4.  Table  of  Atomic  Weights  ....................................  56 

5.  Measures  and  Weights  .....................................  57 


INTRODUCTORY  REMARKS. 


My  object  in  sending  forth  the  following  pages  is  to 
place  in  the  hands  of  chemists  and  those  interested  in  paints 
and  pigments,  a  guide  for  the  practical  analysis  of  such  pro- 
ducts. I  make  no  pretensions  to  having  placed  herein  much 
of  original  matter,  but  have  drawn  freely  from  the  records  of 
chemical  literature  and  authorities  on  the  subject,  to  which  I 
have  added  such  other  matter  as  my  experience  as  au  ana- 
lytical chemist  would  warrant. 

My  aim  has  been  to  detail  methods  for  the  analysis  of 
the  majority  of  white  and  tinted  pigments  and  pigment  mix- 
tures found  in  the  paint  trade,  and  which  the  chemist  may  be 
called  upon  to  examine. 

It  is  assumed  that  the  chemist  is  familiar  with  the  ap- 
paratus, reagents,  etc.,  that  are  required  in  analytical  chemis- 
try, and  for  this  reason  their  descriptions  are  omitted. 

It  has  been  my  endeavor  to  give  such  methods  and  in 
sufficient  detail  that  those  having  but  a  limited  knowledge  of 
the  principles  of  analytical  chemistry  could  successfully 
carry  out  the  analyses.  In  this  class  there  may  be  some  in 
the  paint  trade  who  have  sufficient  knowledge  of  analytical 
chemistry  to  perform  analyses  and  obtain  results  for  their 
own  use.  To  these  I  would  respectfully  suggest  that  the 
details  of  each  determination  be  thoroughly  studied  in  the 
standard  works,  such  as  Fresenius,  in  the  hope  that  such 
research  and  practice  may  lead  to  that  proficiency  which  be- 
longs to  the  technical  chemist. 

For  the  guidance  of  those  having  but  a  limited  experi- 
ence the  following  general  precautions  are  given: 

1st.  Generally  the  reagents  used  should  be  those  known 
as  chemically  pure  (c.  p.)  Should  the  standard  chemicals 
of  known  purity  be  not  at  hand  then  the  reagent  should  be 
especially  tested  and  if  found  impure  be  rejected.  Or  if 
desired,  it  may  be  purified. 


_  2  — 

2nd.  Uee  reagents  intelligently.  Too  much  as  well  as 
too  little  may  cause  errors.  Study  the  reaction  and  the  suc- 
cessful conditions  required. 

3rd.  All  distilled  water  should  be  tested  for  mineral 
salts.  This  may  be  done  by  evaporating  several  litres  to  dry- 
ness  and  should  leave  no  perceptible  residue. 

4th.  The  amount  of  sample  taken  for  analysis  should  be 
governed  by  the  amount  present  of  the  constituent  sought. 
in  general  one  gram  is  a  sufficient  amount,  but  often  times,  if 
the  constituent  be  but  a  trace,  five  times  or  more  may  be 
necessary  to  get  a  sufficient  weighing  amount.  And  again  it 
may  be  that  only  a  fraction  of  a  gram  will  give  a  precipitate 
of  sufficient  size  for  easy  manipulation. 

5th.  If  a  determination  requires  a  special  apparatus, 
first  make  a  blank  test  or  test  with  a  substance  containing  the 
constituents  of  known  amount,  to  make  sure  that  the  appara- 
tus is  in  perfect  working  order.  In  fact  all  determinations 
may  be  practiced,  using  substances  of  known  percentages. 

6th.  In  using  filter  paper  the  size  9  c.  m.,  S.  and  S.  is  to 
be  preferred,  requiring  no  correction,  as  they  are  practically 
ashless.  If  cheaper  grades  be  used,  always  deduct  the  ash 
content.  Little  time  is  saved  by  using  large  filters  as  they 
require  more  washing  and  thereby  increase  the  volume  of  the 
filtrate.  The  Gooch  crucible  and  cone  are  recommended 
whenever  admiesable. 


CHAPTER  I. 


PREPARING  SAMPLES  FOR  ANALYSIS. 

If  the  sample  is  in  the  form  of  a  mixed  or  paste  paint  it 
will  be  advantageous  to  first  free  the  pigments  from  the 
mixing  fluid.  This  may  be  done  in  several  ways. 

When  only  the  analysis  of  the  pigments  is  desired  the 
simplest  method  is  to  wash  out  or  exhaust  the  oil  and  thin- 
ness by  benzine,  gasoline,  petroleum- ether,  benzole,  ether,  etc. 
As  benzine  or  gasoline  are  the  cheapest  they  are  to  be  pre- 
ferred. About  25  grams  of  the  sample,  previously  thoroughly 
stirred,  are  placed  in  a  beaker  of  about  150  c.  c.  capacity  (or 
a  whisky  glass  with  thin  sides)  and  after  adding  the  solvent, 
the  mass  is  stirred  with  a  glass  rod  and  the  pigment  allowed 
to  settle.  When  the  liquid  is  perfectly  clear  draw  off  the 
clear  portion  by  means  of  a  pipette,  again  add  the  solvent, 
stir  and  allow  to  settle.  Usually  three  or  four  applications 
of  the  solvent  will  be  found  sufficient  to  free  the  pigment 
from  oil  and  most  of  the  drier.  Any  traces  of  the  latter  are 
disregarded.  It  is  a  good  plan  to  test  the  solvent  after  the 
second  treatment  by  evaporating  a  small  portion  on  a  watch 
crystal  and  observing  whether  it  leaves  any  residue  of  oil. 
When  ether  is  not  used  it  is  a  good  plan  to  finish  the  extrac- 
tion with  it.  After  drawing  off  the  solvent  as  closely  as 
possible  the  remainder  is  evaporated  on  a  water  bath  and  the 
residue  heated  in  an  air  oven  at  100°  C.  for  about  an  hour. 
Eemove  the  dry  pigment  to  a  glass  or  agate  sorter,  rub  up 
thoroughly  and  pass  through  a  fine  seive.  Place  in  a  well- 
stoppered  bottle  and  label. 

Should  the  sample  be  dry  or  not  mixed  with  oil  it  is  best 
to  heat  in  the  air  oven  at  100°  C.  in  order  to  free  it  from 
moisture.  Then  place  in  bottle  and  keep  stoppered. 

If  it  is  desired  to  ascertain  the  percentage  of  pigments 
and  mixing  fluid  it  may  be  done  by  weighing  the  beaker  and 


—  4  — 

rod,  then  weighing  again  after  adding  the  sample,  the  increase 
in  weight  being  the  amount  of  sample.    Then,  after  exhaust- 
ing  and  drying,  the  difference  in  weight  is  the  amount  of 
mixing  fluid. 
Example:  — 

Weight  of  beaker  rod  and  sample  ..............  42.0771  grams. 

Weight  of  beaker  and  rod  ......................  28.6435 

Weight  of  sample  .......................  13.4336        " 

After  treating  with  solvent:  — 

Weight  of  beaker,  rod  and  sample  ..............  42.0771  grams. 

Weight  of  beaker,  rod  and  pigments  .......   ____  36.0520        " 

Loss  equals  mixing  fluid  .................     6.0251        " 

then  —  -  =  44.858  —  percentage  mixing  fluid  by  weight. 


When  it  is  necessary  to  be  extremely  accurate  iu  getting 
both  the  percentages  of  mixing  fluid  and  pigment  it  will  be 
found  best  to  exhaust  the  sample  in  a  Soxhlet  extractor,  using 
petroleum-ether  or  ordinary  sulphuric  ether  as  a  solvent. 
A  convenient  size  of  Soxhlet  extractor  is  one  inch  diameter  and 
nine  inches  in  length  with  the  arrangement  as  shown  in  the 
cut  on  page  5.  The  inside  tube  is  an  ordinary  test  tube  with 
a  hole  cut  or  blown  in  the  bottom.  The  bottom  of  the  tube  is 
then  packed  with  a  piece  of  cotton  (6).  The  tube  (12)  and 
cotton  are  weighed  first,  then  the  sample  of  the  paint  is 
added,  and  the  whole  weighed  again,  the  increase  being  the 
weight  of  sample  taken.  Another  plug  of  cotton  will  be  found 
necessary  in  cases  when  the  pigment  is  so  light  that  it  floats 
to  the  top  of  the  test  tube.  This  occurs  usually  when  the 
cotton  is  packed  too  tightly  to  permit  the  solvent  to  flow  out  of 
the  bottom  and  often  times  it  will  be  necessary  to  place  a 
small  glass  stopper  on  the  upper  layer  as  a  weight  to  prevent 
the  contents  of  the  tube  from  overflowing  or  floating  to  the 
top.  When  such  an  arrangement  is  necessary  the  whole  tube, 
including  sample  and  two  plugs  of  cotton,  are  weighed,  but 
not  the  glass  which  was  added  as  a  weight.  About  an  ounce 
of  the  solvent,  ether  or  petroleum-ether,  is  then  placed  in  the 
flask  and  the  water  heated  in  the  water  bath  not  quite  to 
boiling  point.  Soon  the  ether  will  begin  to  appear  in  the 


—  5  — 


condenser  and  drop  back  in  the  test  tube  containing  the  paint, 
and,  passing  down  through  the 
sample,  will  fill  up  in  the  tube 
(13)  and  syphon  over.  This 
operation  is  kept  up  until  the 
solvent  liquid  is  perfectly  clear 
and  shows  no  color,  which,  in 
most  cases,  would  be  due  to  oil. 
Usually  about  a  dozen  syphon- 
ings  will  be  sufficient,  but  sam- 
ples vary  and  it  is  best  to  allow 
the  extractor  to  work  until  the 
solvent  syphons  perfectly  color- 
less. The  test  tube  (12)  con- 
taining the  oil-free  paint  is  now 
removed  and  thoroughly  dried 
in  a  drying-oven  then  weighed. 

The  loss  in  weight  equals  the 
oil  present,  and  the  dried  sam- 
ple is  taken  out  to  be  used  for 
the  analysis.  If  it  is  desired  to 
find  the  amount  of  oil,  the  small 
flask  (8)  may  be  weighed  before 
the  operation  and  then  the  ether 
evaporated  on  a  water  bath  heat- 
ed in  an  air  oven  at  100°  C,  for 
15  minutes,  and  the  amount  of 
the  extracted  oil  weighed. 

The  centrifugal  machine,  such 
as  is  used  in  the  separation  of  fat 
in  milk,  may  be  utilized  to  advan- 
tage in  separating  the  pigment 

..  _  from  the  oil  and  thinners.    This 

is  accomplished  by  using  from 

2  waflr  ?nietet  !  WateSh  five  to  ten  grams  of  the  sample, 
and,  after  placing  in  the  tube, 
add  gasoline  to  within  a  half 
inch  from  the  top.  Then  with  a 
glass  rod  stir  the  whole  until  the 

sample  is  thoroughly  mixed  with  the  benzine.     Place  in 


5  Sample  Paint 
fi  Cotton  Plug 
7  Cork  Stopper 


12  Test  Tube 

13  8oxWet  Tube 


—  6  — 

machine  and  revolve  about  ten  minutes  or  until  the  benziue 
is  clear  and  free  from  the  suspended  pigment.  Pour  off  the 
benzine,  which  is  readily  done  as  the  pigment  will  be  thrown 
to  the  bottom  of  the  tube  and  forms  a  hard  cake.  Now  add 
more  benzine,  and,  with  the  aid  of  a  glass  rod,  again  stir 
thoroughly  and  revolve  as  before.  Generally  three  or  four 
treatments  will  complete  the  extraction.  When  the  pigment 
is  removed  with  the  aid  of  a  spatula  and  transferred  to  a 
watch  glass.  Then  dried,  sifted  and  bottled. 

This  method  may  be  found  of  much  value  in  a  labora- 
tory where  many  ground  or  mixed  paints  are  daily  examined 
and  quick  results  desired. 

It  is  the  practice  of  some  paint  chemists  to  treat  the  sample,  if  it 
be  mixed  with  oil,  with  strong  nitric  acid,  to  which  is  added  about  one- 
fourth  water,  and  boil.  Ihe  oil  collects  in  a  gummy  mass  and  is  filtered 
after  diluting.  Wash  the  filter  with  hot  water  acidulated  with  nitric 
acid.  The  filtrate  will  contain  soluble  pigments  and  the  insoluble  por- 
tion will  remain  on  filter  with  the  oil. 

This  method  is  not  to  be  recommended  except  in  cases  where  a 
rough  test  is  deeired  to  ascertain  the  bases  present. 


CHAPTER  II. 


WHITE  PIGMENTS. 

i.  Calcium  Carbonate,  (  Whiting. )—  Whiting  consists 
of  carbonate  of  calcium  (CaCO3),  with  small  amounts  of 
magnesium  carbonate,  silica,  iron  and  alumina,  moisture  and 
possibly  sulphate  of  calcium.  The  analysis  is  not  often  re- 
quired as  its  cheapness  offers  no  inducement  for  adulteration, 
yet  the  paint  manufacturer  or  chemist  may  be  called  upon  to 
choose  between  several  samples  and  a  plan  for  its  examina- 
tion is  herewith  given. 

Moisture. — Take  about  two  grams  on  a  watch  glass, 
weigh  carefully,  place  in  an  air  oven,  and  heat  at  a  temperature 
of  100°  C.,  until  the  weight  is  constant.  The  loss  is  the 
moisture. 

Silica  and  Insoluble  Matter. — Dissolve  one  gram  of  the 
dried  sample  in  a  200  c.c.  covered  beaker  with  about  10  c.c. 
strong  hydrochloric  acid  and  100  c.c.  of  water.  When  effer- 
vesence  is  over  and  a  white  insoluble  residue  appears,  it 
indicates  that  silica  is  present.  Transfer  to  a  platinum  dish 
and  bring  to  dryness  on  a  water  bath,  then  heat  in  an  air  oven 
at  100°  C.,  to  drive  off  all  the  water  and  and  render  the  silica 
insoluble.  When  the  smell  of  hydrochloric  acid  has  disap- 
peared, remove  from  oven  and  moisten  with  hydrochloric 
acid,  then  add  about  30  c.c.  water  and  heat  until  everything 
but  silica  is  dissolved.  This  will  settle  to  the  bottom  and  is 
filtered  off  on  a  small  ashless  filter  and  washed  with  hot  water. 
Allow  to  drain  well  in  funnel,  place  filter  in  a  weighed  plat- 
inum crucible  and  ignite  until  nothing  but  the  white  silica 
(SiO2)  remains.  In  igniting  a  wet  or  moist  precipitate  a  little 
skill  is  required  to  prevent  loss  from  spirting.  If  the  opera- 
tor will  be  careful  to  incline  the  crucible  on  the  triangle,  and 
allow  the  gas  flame  to  play  on  the  outer  edge  first,  and  grad- 
ually heat  the  whole  crucible  until  the  paper  becomes  charred, 


—  8  — 

forming  a  sort  of  envelope  with  the  precipitate  inside,  no 
trouble  will  be  occasioned  from  loss  and  the  paper  will 
gradually  burn  away.  The  precipitate  is  then  cooled  in  the 
dessicator  and  weighed. 

Iron  and  Alumina. — To  the  filtrate  add  a  few  drops  of 
nitric  acid,  wRrru  to  oxidize  the  iron,  then  add  5  grams  chemi- 
cally pures  ammonium  chloride,  then  ammonia  in  excess  and 
boil  until  excess  of  ammonia  is  driven  off.  Filter,  wash  with 
hot  water  an$  ignite  the  wet  precipitate  as  in  silica  determina- 
tion. Should  a/?hite  flocculent  precipitate  appear,  it  shows 
that  enough  aticfrnonium  chloride  has  not  been  used  to  prevent 
the  calcium  from  precipitating  as  hydrate,  and  it  will  be 
necessary  to  keep  adding  ammonium  chloride  until  nothing 
but  iron  and  alumina  are  thrown  down.  Weight  equals  iron 
oxide  and  alumina  (Fe2O3  and  A12O3).  As  the  amount  of 
iron  and  alumina  is  very  small  in  whiting,  it  will  not  be 
necessary  to  separate  them. 

Calcium  Carbonate. — To  the  filtrate  from  the  iron  and 
alumina  add  ammonia  in  excess.  Now  add  drop  by  drop  and 
with  constant  stirring,  ammonium  oxalate  (about  40  c.c. 
saturated  solution )  until  the  precipitate  csases  to  form  and 
the  ammonium  oxalate  is  in  considerable  excess.  It  is  neces- 
sary to  add  a  sufficient  amount  to  combine  with  the  magne- 
sium as  well  as  the  calcium.  Allow  the  precipitate  to  settle 
in  a  warm  place  for  several  hours,  preferably  over  night. 
Then  pour  the  clear  supernatant  fluid  through  an  ashless  filter 
until  the  precipitate  is  covered  with  about  a  half  inch  of  the 
liquid.  Add  hydrochloric  acid  until  the  precipitate  is  dis- 
solved, then  40  c.c.  hot  water,  ammonia  in  excess,  add  5  c.c. 
ammonia  oxalate,  stir  well  and  allow  to  stand  again  for 
several  hours  and  filter.  The  filter  is  washed  well  with  hot 
water  and  then  dried.  The  object  in  dissolving  and  reprecip- 
itating  the  calcium  oxalate  is  to  make  sure  that  no  magne- 
sium is  precipitated.  In  whiting  it  is  not  absolutely  neces- 
sary, as  the  magnesium,  if  any  is  in  small  amounts,  but  in 
cases  where  much  magnesium  is  present,  it  is  quite  essential 
for  complete  precipitation.  Proceed  with  the  filtrate  as 
directed  in  magnesium  determination. 

The  dried  calcium  oxalate  may  be  weighed  either  as 
calcium  oxide  or  calcium  sulphate.  If  the  former  method  is 


—  9  — 

to  be  used  the  ordinary  heat  of  a  Bunsen  burner  will  not  be 
sufficient  to  drive  off  all  the  carbon  dioxide,  and  it  will  be 
necessary  to  heat  over  a  blast  lamp  until  after  several  weigh- 
ings, the  weight  is  constant.  The  weight  of  calcium  oxide 
(Cap)  multiplied  by  1.784  gives  the  CaCO,  or  carbonate  of 
calcium.  If  the  calcium  oxalate  is  to  be  converted  to  calcium 
sulphate  proceed  as  follows:  Moisten  the  dried  precipitate 
of  calcium  oxalate  with  dilute  sulphuric  acid  (1  part  acid, 
3  parts  water)  and  heat  cautiously  until  the  excess  of  acid  is 
driven  off  and  the  precipitate  is  white.  Cool.  Add  a  few 
drops  of  concentrated  sulphuric  acid  and  again  heat  cautiously 
by  allowing  the  gas  flame  to  play  gently  back  and  forth  on 
the  crucible  until  the  white  fumes  are  entirely  driven  off. 
Next  heat  to  rednees  for  about  five  minutes,  cool  and  weigh. 
The  weight  of  calcium  sulphate  multiplied  by  .7349  gives 
the  CaCO3. 

Magiiesium  Carbonate. — To  the  combined  filtrates  from 
the  calcium  oxalate  precipitate  add  a  large  excess  of  ammonia 
until  it  is  strongly  alkaline,  then  an  excess  of  a  solution  of 
sodium  phosphate,  stir  well  without  permitting  the  rod  to 
touch  the  sides  of  the  beaker,  allow  to  stand  12  hours  (best 
over  night)  in  a  cool  place,  filter  and  wash  with  ammonia 
water  (1  part  ammonia,  2  parts  water.)  If  the  combined 
filtrate  exceeds  100  c.c.  add  hydrochloric  acid  in  slight 
excess,  evaporate  to  100  c.c.,  cool  and  proceed  as  above.  A 
rubber  tipper  rod  will  be  found  very  useful  to  rub  the  crys- 
talline precipitate  from  the  side  of  the  beaker.  Dry.  Be- 
move  precipitate  from  paper  with  a  spatula  to  a  piece  of 
black  glazed  paper,  then  burn  the  paper  first  in  a  weighed 
porcelain  crucible,  cool,  add  precipitate  and  ignite  strongly 
until  the  precipitate  is  white  or  nearly  so,  and  has  a  constant 
weight  Weigh  the  magnesium  pyrophosphate  (Mg2P2O7) 
and  multiply  by  factor  .7575  to  convert  to  MgCO3. 

Sulphate. — To  estimate  any  sulphuric  acid  that  might 
be  present  as  sulphates  proceed  as  follows:  5  grams  of  the 
sample  are  dissolved  in  hydrochloric  acid  and  any  insoluble 
matter  filtered  off  and  the  filter  washed  with  hot  water.  To 
the  warm  filtrate,  add  drop  by  drop  with  constant  stirring,  a 
solution  of  barium  chloride  until  the  precipitate  ceases  to 
form  and  the  precipitant  is  in  excess.  Allow  to  stand  in  a 


-  10  - 

warm  place  over  night,  filter,  wash  with  hot  water  and  after 
the  preciDitate  is  drained  well,  ignite  as  in  silica  determination. 
Weigh  the  white  precipitate  of  barium  sulphate  (BaSO4)  and 
multiply  by  factor  .583  to  convert  to  calcium  sulphate  (CaSO4) 
Then  multiply  the  calcium  sulphate  found  by  factor  .735  to 
convert  to  calcium  carbonate,  subtract  this  from  the  total 
calcium  carbonate  and  the  difference  is  the  amount  of 
calcium  carbonate. 

2.  Gypsum  (Sulphate  of  Calcium,  Terr  a  Alba). — Gypsum 
is  found  quite  abundantly  and  often  in  a  state  of  great  purity. 
It  has  the  chemical  composition  of  CaSO42H2O,  and  if  the 
water  be  driven  off  by  heat  the  well  known  Plaster  of  Paris 
will  be  left,  which  has  the  property  of  again  combining  with 
water  to  "set"  into  a  white  hard  mass.     When  used  as  a  pig- 
ment gypsum  is  usually  fully  hydrated. 

Its  analysis  is  not  attended  with  any  difficulty.  The  deter- 
minations ordinarily  to  be  made  are:  insoluble  matter,  (such 
as  clay,  sand,  etc., )  calcium,  sulphuric  acid,  water  and  any 
small  amounts  of  iron  and  alumina  or  magnesium.  Proceed 
as  directed  on  page  7  in  the  analysis  of  whiting  for  the  deter- 
minations of  soluble  matter,  iron  and  alumina,  calcium  and 
magnesium,  and  sulphuric  acid.  To  determine  water,  use 
one  gram  and  ignite  in  a  platinum  erucible  to  constant  weight. 
For  sulphuric  acid  determination  use  1  gram  instead  of  5  as 
in  whiting. 

The  bases  and  acids  in  gypsum  are  usually  reported 
without  combining  them: 

ANALYSES  OP  NATURAL  GYPSUM  BY  THE  AUTHOR. 

No.  i.        No.  2. 

Calcium  Oxide 32.88        32.32 

Sulphuric  Acid 45.79        45.76 

Water 20.98        21.39 

Silica c undet  .07 

Iron  Oxide undet  .01 

99.65        99.55 

3.  China  Clay  (Kaolin.) — China  clay  is  a  natural  pro- 
duct and  is  essentially  a  hydrated  silicate  of  alumina  of  the  ap- 
proximate composition,  silica  47  per  cent,  alumina  40  per  cent, 
and  water  18  per  cent.,  and  has  a  formula  2  SiO2A)2O32H2O. 
It  is  not,  however,  of  constant  composition   as   clays   from 


—  11  — 

different  localities  vary  and  usually  contain  small  quantities 
of  iron  oxide  with  calcium,  magnesium,  potassium  and  sodium 
silicates. 

The  following  is  the  method  of  analysis: 

The  sample  after  being  pulverized  and  dried  at  100° CL, 
for  about  &n  hour  is  kept  in  a  well  stoppered  bottle.  As  clay 
is  only  slightly  acted  on  by  acids,  it  will  be  necessary  to  fuse 
it  to  effect  decomposition. 

Proceed  as  follows: 

Silica* — One  gram  is  thoroughly  mixed  in  an  agate 
mortar  with  10  grams  sodium  carbonate  and  about  a  half 
a  gram  of  potassium  nitrate  and  placed  in  a  capacious 
platinum  crucible  and  covered.  The  mixture  should  not  fill 
the  crucible  more  than  half  fall.  Fuse  over  the  blast  lamp, 
run  it  carefully  up  the  sides  of  the  crucible,  and  when  the 
fused  mass  is  quite  clear  and  quiet,  allow  to  cool.  Place  the 
crucible  and  cover  in  a  beaker,  add  water  until  the  crucible  is 
just  covered  and  digest  on  a  hot  plate  until  the  fused  mass 
is  thoroughly  disintegrated.  Remove  the  crucible  ( and  cover  ) 
wash  inside  and  out  with  hot  water,  allowing  the  washings  to 
run  back  in  the  beaker.  Pour  the  solution  into  a,  good  sized 
platinum  dish,  cover  witli  a  watch  glass,  and  then  add  care- 
fully, by  raising  the  watch  glass  a  little,  hydrochloric  acid  in 
slight  excess.  Add  a  few  drops  of  hydrochloric  acid  to  the 
crucible  and  wash  into  the  platinum  dish.  The  cover  should 
also  be  clean.  After  the  effervesence  is  over,  wash  off  the  watch 
glass  with  hot  water  and  place  the  dish  in  a  hot  air  oven  or 
on  water  bath  and  evaporate  to  dryness.  It  may  be  necessary 
to  break  the  crust  occasionally  by  stirring  with  a  platinum 
rod  which  is  afterward  washed,  the  washings  going  into  the 
dish.  Dissolve  the  dried  mass  in  water  and  again  bring  to 
dry  ness  and  heat  in  oven  at  about  110°  C.,  until  all  smell  of 
hydrochloric  acid  is  gone.  Then  add  10  c.c.  strong  hydrochloric 
acid  and  about  100  c.c.  hot  water.  Warm.  Filter  off  the 
insoluble  silica,  washing  with  hot  water  acidulated  with  a 
little  hydrochloric  acid,  dry,  ignite  first  with  Bunsen  then 
over  the  blast  and  weigh.  Weight  equals  silica  (SiO2). 

Oxide  of  Iron  and  Alumina. — Acidulate  the  filtrate  from 
the  SiO2  with  hydrochloric  acid  and  concentrate  to  about 
100  c.c.  then  add  ammonia  in  slight  excess.  Boil  until  it  smells 


—  12  — 

bet  slightly  of  it  and  allow  to  settle.  Pour  off  the  clear  super- 
natant liquid,  add  about  100  c.c.  of  hot  water,  allow  to  settle  and 
again  decant.  Eepeat  several  times,  stirring  the  preci- 
pitate and  added  water  each  time,  then  transfer  precipitate 
to  a  filter  using  hot  water  and  rubber  tipped  rod  to  clean  the 
precipitate  from  the  beaker.  Wash  precipitate  once  or  twice 
with  hot  water,  then  drain  well  and  ignite  wet.  Weight 
equals  Fe?O3-\-A\yO3>  If  it  is  desired  to  get  the  oxide  of  iron 
and  alumina  separately,  mix  the  oxides  with  about  8  times 
their  weight  of  carbonate  of  soda  in  a  platinum  cruc  ble  and 
fuse  over  the  blast  lamp.  Digest  crucible  and  contents  in 
hot  water,  and  when  the  fused  mass  is  softened  throw  on 
filter  and  wash  slightly  with  water,  then  dissolve  in  hydro- 
chloric acid  and  estimate  the  iron  in  the  solution  either  gr»iv- 
imetrically  or  volumetrically  by  permanganate  or  bichromate 
of  potash. 

The  gravimetric  method  is  often  more  convenient  on 
account  of  its  weighing  the  iron  direct.  In  this  method,  after 
fuzing  the  oxides,  filtering,  washing  and  dissolving  in  hydro- 
chloric acid,  the  iron  is  separated  from  the  alumina  by  preci- 
pitation with  ammonium  sulphide.  Add  to  the  solution  con- 
taining the  iron  and  aluminum  as  chlorides  about  five  times 
the  weight  of  the  oxides,  of  citric  acid,  and  excess  of  ammonia. 
The  solution  should  remain  perfectly  clear.  If  it  does  not 
remain  BO  add  hydrochloric  acid  in  slight  excess,  then  a  few 
grams  more  of  citric  acid  and  excess  of  ammonia.  Now  heat 
the  clear  solution  to  boiling  and  add  solution  of  sulphide  of 
ammonium  in  slight  excess.  Allow  to  settle  and  filter,  wash- 
ing the  precipitate  with  water  containing  a  little  ammonium  sul- 
phide. Keep  the  funnel  covered  with  a  watch  glass  during  the 
washing.  When  the  precipitate  and  paper  have  been  washed 
four  or  five  times  and  the  paper  is  drained  quite  dry,  pour  on 
the  filter  hot  dilute  hydrochloric  acid,  and  allow  the  solution 
to  run  into  tho  beaker  in  which  the  precipitate  was  made. 
Wash  with  hot  water.  Now  add  a  few  drops  of  nitric  acid  and 
evaporate  to  dryness  in  the  beaker,  dissolve  in  as  little  hydro- 
chloric as  is  necessary  to  effect  solution,  dilute  to  about  25  c.c. 
and  filter.  Wash  paper  with  hot  water.  Precipitate  the  iron 
with  ammonia,  boil,  filter,  wash,  and  ignite  in  the  same  man- 
ner as  described  for  the  estimation  of  total  iron  and  alumina. 


—  13  — 

The  weight  equals  ferric  oxide  (Fe2O3)  which  deducted  from 
the  total  oxides  of  iron  and  alumina  (Fe2O3+Al2O3)  leaves 
the  alumina  (A12O3). 

Following  is  the  method  by  using  permanganate  of  pot- 
ash. Prepare  a  solution  of  permanganate  by  dissolving  ^fr 
grams  of  the  c.p.  salt  in  one  litre  of  water.  When  all  is  in 
solution  pour  it  into  a  glass  stoppered  litre  bottle  and  shake 
thoroughly.  (After  its  equivalent  in  iron  is  found  it  should 
be  labeled  and  kept  in  a  dark  place  and  its  strength  ascer- 
tained from  time  to  time).  Standardize  the  solution  by 
means  of  ferrous  sulphate  (FeSO47H2O).  Take  exactly  5 
grams  of  the  c.p.  salt  and  dissolve  in  300  c.c.  water,  add 
10  c.c.  sulphuric  acid  and  cool  by  allowing  the  hydrant  water 
to  run  over  the  outside  of  the  flask.  Now  fill  a  50  c.c.  bur- 
ette (glass  cock)  with  the  permanganate  solution  exactly  to 
the  mark  and  allow  it  to  run  into  the  ferrous  sulphate  solu- 
tion, drop  by  drop,  until  a  faint  pink  tint  is  obtained,  which 
shows  that  the  iron  is  all  oxidized  and  the  one  drop  excess 
of  permanganate  colors  the  solution.  It  is  best  to  repeat  the 
operation  several  times  and  take  an  average. 

Pure  ferrous  sulphate  contains  20.1439  per  cent  of  iron 
(Fe)  then  .5  grams  contains  .1007  grams  iron  and  if  this 
took  15  c.c.  of  the  permanganate  solution  then  I  c.c.  would 
equal  .0067  grama  iron.  With  this  solution  we  can  now  find  the 
amount  of  iron  in  an  unknown  solution.  To  do  this  the  iron 
must  first  be  reduced  to  the  ferrous  condition  by  means  of 
metallic  zinc  or  some  other  deoxidizer.  To  use  zinc  transfer 
the  solution  of  iron  chloride  obtained  in  the  above  fusion  to  a 
flask  of  about  500  c.c.  capacity  and  add  3  grams  (roughly 
weighed)  of  the  granulated  zinc,  warm  slightly,  and  allow  the 
action  to  go  on  until  the  solution  is  perfectly  colorless.  Then 
add  a  few  c.c.  of  hydrochloric  acid  to  dissolve  the  remaining 
bits  of  zinc  and  if  the  solution  still  remains  colorless  it  may  be 
considered  deoxidized.  If  not,  more  zinc  must  be  added  and  the 
action  allowed  to  continue.  When  the  solution  is  completely 
deoxidized  add  a  mixture  of  10  c.c.  sulphuric  acid  and  10  c.c. 
water,  wash  off  the  funnel  allowing  the  water  to  run  down  the 
neck  of  flask  and  then  cool  by  allowing  the  hydrant  water  to 
run  on  the  outside  of  the  flask.  Now  run  in  the  standard  solu- 
tion of  permangate  from  the  burette  until  the  pink  tint  is  ob- 


—  14  — 

tained.  The  amount  of  permanganate  solution  used,  less  coi- 
rection  for  zinc,  is  then  read  and  knowing  its  strength  in  iron 
the  amount  of  iron  in  the  sample  is  readily  calculated.  If  we 
found  it  required  5  4  c.c.  standard  permanganate  solution  with 
a  strength  1  c.c.=.0067  grams  Fe.,  then  54 X. 0067 =.03618  grams 
Fa,  which  multiplied  by  factor  1.428  gives  .0517  Fe2O3.  Hav- 
ing now  the  weight  of  oxide  of  iron  and  alumina  and  oxide 
of  iron  the  difference  equals  alumina. 

Calcium  and  Magnesium. — Concentrate  the  filtrate  and 
decantation  water  from  precipitation  of  the  iron  and  aluminum 
first  adding  a  little  hydrochloric  acid,  to  about  100  c.c.  and 
proceed  as  detailed  in  the  analysis  of  "Whiting"  for  the 
estimation  of  calcium  and  magnesium. 

Potassium  and  Sodium. — The  following  method  known 
as  the  J.  Lawrence  Smith  method  will  be  found  probably  as 
expeditious  and  accurate  as  any  for  the  determination  of  the 
alkaline  salts.  Weigh  out  1  gram  of  the  clay  and  rub  up  in  a 
mortar  first  with  about  a  gram  of  c.  p.  ammonium  choride 
and  then  add  10  grams  c.  p.  carbonate  of  calcium  and  mix 
thoroughly.  Transfer  to  a  large  platinum  crucible,  cover  and 
heat  for  a  few  moments  to  decompose  the  ammonium  chloride. 
Now  place  the  crucible  on  the  triangle  and  adjust  the  flame 
so  that  the  crucible  is  cherry  red  and  keep  at  this  tempera- 
ture for  about  one  hour.  Remove  flame  and  cool.  Place 
crucible  with  contents  and  cover  in  a  beaker,  add  about  100  c.c. 
of  water  and  heat  until  the  mass  is  thoroughly  slaked.  Take 
out  the  crucible  and  wash  with  hot  water,  allowing  water 
to  run  back  in  beaker  and  filter.  The  filtrate  contains  the 
alkalies  with  impurities.  Add  about  2  grams  c.p.  ammonium 
carbonate  and  about  5  drops  of  ammonia  and  evaporate  to 
about  25  c.c.  Filter  off  the  calcium  carbonate,  wash  slightly 
with  water.  Add  more  ammonium  carbonate  to  make  sure 
that  all  the  calcium  has  been  precipitated.  If  a  precipitate 
appears,  evaporate  to  a  small  bulk  and  again  filter.  Usually 
two  or  three  treatments  will  take  out  all  the  calcium.  Now 
add  a  few  drops  of  hydrochloric  acid,  evaporate  to  dry  ness  in 
a  weighed  platinium  dish,  then  heat  carefully  not  quite  to 
redness  until  white  fumes  of  ammonium  chloride  cease  to 
come  off,  cool  and  weigh  as  chlorides  of  sodium  and  potassium 
(NaCl+KCl).  Add  a  few  c.c.  of  water  to  the  dish  and  the 


—  15  — 

chlorides  should  dissolve  completely  to  a  clear  solution.  If 
any  insoluble  matter  appears,  it  must  be  filtered  off  and  the 
filter  washed  once  or  twice  with  hot  water  and  the  filtrate  again 
brought  to  drynesa  and  weighed  as  before.  If  no  insoluble 
matter  appears  add  a  solution  of  platinic  chloride  in  excess  and 
evaporate  in  a  water  bath  until  it  begins  to  cake,  then  add 
about  20  to  50  c.c;  of  80  per  cent,  alcohol  to  dissolve  the  excess 
of  platinic  chloride,  stir  and  allow  the  crystals  of  potassium 
platinic  chloride  to  settle,  filter  in  a  previously  dried  and 
weighed  filter  washing  with  80  per  cent,  alcohol  until  the 
washings  come  through  colorless.  Dry  in  oven  at  110°  0., 
and  weigh  quickly.  Weight  equals  the  potassium  platinic 
chloride  ( K2PtCl6 ),  multiply  by  factor  .1939  gives  K2O.  Then 
multiply  K2PtCl6  by  factor  .3055  which  will  give  KC1.  Deduct 
this  weight  from  the  total  KC1  and  NaCl,  difference  equals 
NaCl,  which  multiplied  by  the  factor  .5306  gives  NaaO. 

Water. — To  estimate  the  combined  water  ignite  one  gram 
of  the  clay  to  redness  in  a  platinum  crucible  until  the  weight 
remains  constant.  The  loss  equals  water. 

The  following  analysis  of  China  clays  are  given  by 
Hurst: 

Cornwall.        China.         America.        French. 

Silica  (SiOa) 46.78  50.50  47.13  48.37 

Mumina  (A12O3) 39.60  33.76  36.76  34.9o 

Water  (H2O) 13.16  11.22  15.13  12.62 

Potash  (K2O) 0.12  1.90  1.76 

Ferric  Oxide  (Fe2O3)...      0.09  1.80  trace  

Lime(CaO) 0.07  0.04  0.24 

Magnesia  (MgO) 0.80  

99.82  99.98  99.06  97.94 

4.  Silica  (Silex.)— Silica  is  a  natural  product  of  the 
composition  SiO2,  has  quite  an  extended  use  as  a  pigment  and 
is  used  largely  in  the  manufacture  of  wood  fillers.  It  is 
light,  white,  inert  and  insoluble  in  acids.  Some  of  the  brands 
are  made  by  pulverizing  crystallized  quartz  (which  is  pure 
silica)  and  others  are  found  as  powder  of  sufficient  fineness 
for  use  without  any  further  preparation.  As  silica  is  found 
in  a  pure  condition  an  analysis  is  not  often  required.  Occa- 
sionally the  relative  purity  of  several  brands  may  be  desired 
in  which  case  the  determination  of  silica  alone  will  be  suffi- 


-  16  - 

cient    Other  constituents  may  be  lime  and  magnesia,  iron 
and  water,  with  possibly  traces  of  alkalies.     For  the  analysis 
proceed  as  detailed  in  the  analysis  of  China  clay,  page  10. 
ANALYSES  OF  SILICA  BY  THE  ATJTHOR. 

No.  1  No.  2  No.  3  No.  4 

Silica 99.40  97.70  98.01  98.14 

Moisture 12  undet            .32 

Potassium  Oxide  . .     . .  undet  undet  .14  .24 


99.52  97.70  98.15  98.70 

5.  Barium  Sulphate  (Baryies,  Blanc  Fixe.) — Barium 
sulphate  is  used  largely  as  a  cheapener  in  paints  but  its 
analysis  is  not  very  often  required.  It  consists  of  about 
98  to  98.8  per  cent,  barium  sulphate  in  the  best  grades,  with 
small  amounts  of  calcium  sulphate,  silica  or  clay,  iron  and 
alkaline  salts.  It  is  usually  desired  to  ascertain  only  the 
percentage  of  barium  sulphate  (BaSO4)  for  which  the  fol- 
lowing plan  of  analysis  may  be  used: 

Barium  Sulphate. — One  gram  of  the  dried  sample  is 
mixied  in  a  glass  or  agate  mortar  with  seven  grams  sodium 
carbonate  and  three  grams  potassium  carbonate  and  then 
fused  over  a  blast  lamp  in  a  platinum  crucible,  and  the 
crucible  and  contents  when  cool,  placed  in  a  beaker  and 
covered  with  water.  Now  digest  until  the  fused  mass  is 
detached  from  the  crucible  and  the  barium  carbonate  that  is 
formed  has  settled.  Filter  and  rub  the  crucible  clean  with  a 
rubber-tipped  rod.  Wash  several  times  with  hot  water. 
Dissolve  the  barium  carbonate  on  the  filter  with  warm  hydro- 
chloric acid  (1  part  acid,  3  parts  water)  placing  a  watch 
crystal  on  top  of  funnel  to  prevent  loss  from  effervesence. 
Eepeat  the  acid  treatment  until  all  is  dissolved,  and  thoroughly 
wash  the  paper  with  hot  water.  The  solution  now  contains 
the  barium  as  chloride.  Heat  to  boiling,  and  while  hot  add 
dilute  sulphuric  acid  (1  part  acid,  3  parts  water)  with  con- 
stant stirring  until  a  precipitate  ceases  to  form.  Allow  to 
stand  about  four  hours  in  a  warm  place,  then  filter,  washing 
the  precipitate  several  times,  first  by  decantation  and  then  on 
filter  with  hot  water.  It  is  best  to  use  a  double  filter  as  the 
precipitate  has  a  great  tendency  to  run  through.  Dry  and 
ignite,  first  separating  the  precipitate  as  clean  as  possible  from 


—  17  — 

the  paper.  Weight  obtained  multiplied  by  100  gives  the 
percentage  of  barium  sulphate. 

Qualitative  Tests  for  Barytes. — To  detect  barium  sul- 
phate in  a  mixture  of  pigments,  such  as  a  mixed  paint,  dis- 
solve about  two  grams  in  a  mixture  of  10  c.  c.  cone.  c.  p. 
hydrochloric  acid  and  30  c.  c.  water  and  boil  for  five  minutes. 
Filter  and  wash  the  insoluble  residue  which  may  contain 
barytes,  with  hot  water.  Dry  the  precipitate,  separate  from 
paper  and  apply  the  following  tests:  Mix  a  small  portion 
with  dry  c.  p.  sodium  carbonate  on  a  piece  of  stick  charcoal 
(first  digging  out  a  round  hole)  moisten  with  water  and 
fuse  with  a  blow-pipe.  "When  cool  place  the  fused  mass  on 
a  bright  silver  coin,  add  a  few  drops  of  water  and  if  barium 
sulphate  is  present  the  coin  will  be  blackened  owing  to  the 
formation  of  silver  sulphide.  If  lead  sulphate  or  calcium 
sulphate  were  in  the  sample  they  will  go  into  solution  by  the 
treatment  with  hydrochloric  acid.  The  insoluble  residue 
may  be  again  confirmed  by  the  flame  test  Bend  the  end  of 
a  clear  platinum  wire  into  a  email  loop  in  which  pick  up 
some  of  the  material  to  be  tested  and  moisten  with  dilute 
hydrochloric  acid.  Now  hold  steadily  in  the  outer  edge  of  a 
Bunsen  burner  flame  until  a  sharp  point  of  the  material  is 
hot  and  if  barytes  is  present  a  yellowish  green  tint  will  be 
imparted  to  the  flame.  This  test  is  a  little  difficult  to  make 
at  first  as  the  tint  appears  in  flashes,  but  with  practice  it  will 
be  found  very  decisive.  It  is  a  good  plan  to  try  the  flame 
test,  using  pure  barium  sulphate. 

In  the  presence  of  clay  or  silica  the  barytes  may  be  in 
such  a  small  amount  that  the  flame  test  or  blow-pipe  test 
may  not  be  decisive  enough  to  pronounce  the  presence  of 
barytes  with  certainty.  In  such  cases  it  is  best  to  fuse  about 
one  gram  of  the  insoluble  residue  with  sodium  carbonate  and 
proceed  as  detailed  above  for  the  estimation  of  barytes,  and  if 
it  is  desired  to  further  confirm  the  precipitate  obtained  with 
sulphuric  acid,  it  may  be  done  by  the  flame  or  fusion  tests. 

6.  Magnesium  Carbonate  (Magnesite.) — Insoluble  Mat- 
ter.— Add  about  20  c.c.  water  to  one  gram  of  the  sample  and 
then  about  10  c.c.  cone,  hydrochloric  acid,  cover  until  efferves- 
cence ceases.  Warm  to  complete  the  solution,  allow  to  settle 
and  filter,  washing  the  filter  thoroughly  with  warm  water. 


—  18  — 

Dry,  ignite  paper  and  residue  in  platinum  crucible.  Weights 
equals  insoluble  matter. 

Oxide  of  Iron  and  Alumina. — Add  ammonia  to  the  ni- 
trate in  slight  excess,  boil  until  the  excess  is  driven  off  and 
filter,  washing  with  hot  water.  Dry,  ignite  and  weigh  oxide 
of  iron  (Fe2O3)  and  aluminum  (A12O3).  As  the  amount  is 
usually  small,  their  separation  is  not  required. 

Calcium  Carbonate. — To  the  hot  filtrate  add  ammonia  to 
quite  strong  alkaline  reaction,  and  if  a  precipitate  formed, 
add  ammonium  chloride  until  dissolved.  Now  add  solution 
of  ammonium  oxalate  until  the  precipitate  ceases  to  form 
and  the  ammonium  oxalate  is  in  excess.  Let  stand  in  warm 
place  for  four  hours  and  filter,  wash  and  ignite  as  in  whiting. 
Multiply  calcium  sulphate  (CaSO4)  by  .7352  to  convert  to  cal- 
cium carbonate  (  CaCO3 ).  If  weighed  as  calcium  oxide  (  CaO ), 
use  factor  1.7857. 

Magnesium  Carbonate. — Concentrate  filtrate  and  wash- 
ings to  about  100  c.c.,  then  add  ammonia  until  the  solution 
smells  strongly  of  it  and  cool  by  standing  beaker  in  a  basin 
of  cold  water.  When  cold,  add  drop  by  drop  with  constant 
stirring  a  cold  clear  solution  of  sodium  phosphate  in  excess 
and  stir  vigorously  for  several  minutes,  taking  care  that  the 
stirring  rod  does  not  touch  the  sides  of  the  beaker.  Stand 
in  a  cool  place  over  night.  Filter  off  the  supernatant  clear 
solution  and  wash  the  precitate  several  times  by  decantation, 
using  a  mixture  of  1  part  ammonia  and  2  parts  water. 

Then  transfer  precipitate  to  filter,  cleaning  the  sides  of 
the  beaker  with  a  rubber  tipped  rod.  Continue  the  washing 
on  the  paper  until  a  few  c.c.  of  the  filtrate,  to  vrlaich  has  been 
added  a  drop  of  nitric  acid,  gives  only  a  slight  opalesence 
with  a  solution  of  silver  nitrate.  Now  proceed  to  dry  and 
ignite  precipitate  as  directed  in  whiting,  p.  9,  calculating  to 
magnesium  carbonate. 

Pure  magnesite  consists  of  52.4  per  cent,  carbonic  acid 
(CO2)  and  47.6  per  cent,  magnesia  (MgO)  and  is  rarely  found 
in  such  purity,  but  contaminated  with  iron  alumina,  lime  and 
moisture. 

7.  Hagnesium  Silicate  (Talc,  Soapstone,  Steatite.)— 
This  material  is  a  natural  product  containing  about  60% 
silica,  30%  magnesium  oxide  and  impurities,  consisting  of 


—  19  — 

small  amounts  of  water,  iron,  alumina,  calcium,  etc.  Its 
analysis  is  seldom  required,  but  if  desired  the  method  given 
on  p.  11  for  china  clay  may  be  used,  bearing  in  mind  that  the 
reagent,  sodium  phosphate,  used  in  precipitating  magnesium, 
must  be  largely  increased  to  insure  the  complete  precipita- 
tion. 

To  estimate  the  water,  heat  one  gram  in  a  porcelain 
crucible,  using  a  strong  heat  of  a  blast  lamp  as  the  water  is 
not  expelled  as  readily  as  that  in  clay.  Bepeat  the  heating 
until  the  weight  remains  constant. 

8.  Zinc  Oxide  (Zinc  White.)— Zinc  oxide  is  used  to  an 
enormous  extent  at  the  present  day  as  a  pigment,  and  is  found 
in  a  majority  of  the  mixed  paints.  Being  an  artifical  product, 
its  composition  varies  and  the  price  is  governed  by  the  per- 
centage of  oxide  of  zinc  it  contains,  the  best  grades  approxi- 
mating 100  per  cent,  zinc  oxide,  while  some  of  the  cheaper 
products  contain  more  or  less  lead  compounds,  either  as  sul- 
phates or  oxides  and  possibly  sulphate  of  zinc.  The  latter 
element  is  considered  harmful,  as  it  is  soluble  in  water  and 
is  liable  to  cause  the  paint  "streak."  Zinc  oxide  is  rarely 
adulterated. 

Insoluble  Matter. — For  the  analysis,  take  one  gram  of 
the  previously  dried  (in  air  oven  at  100°  C. )  sample  and  add 
about  100  c.c.  hot  water,  then  10  c.c.  strong  hydrochloric  acid 
and  boil.  The  zinc  oxide  and  sulphate  of  lead  (also  zinc 
sulphate  and  lead  oxide)  will  go  into  solution  and  any  insoluble 
matter  such  as  sand  or  clay,  as  natural  impurities,  settle  out. 
Filter  on  small  ashless  filter  and  ignite  as  in  whiting,  page  7. 

Lead. — Add  ammonia  to  the  filtrate  until  nearly  neutral, 
but  is  still  acid,  then  pass  a  rapid  stream  of  hydrogen  sul- 
phide gas  into  the  solution  until  it  is  saturated.  Warm  and 
let  stand  until  precipitate  is  settled.  Filter  and  wash  the 
precipitate  with  water  containing  hydrogen  sulphide,  allow- 
ing the  wash  water  to  run  into  the  filtrate.  The  precipitate 
will  contain  the  lead  as  sulphide.  (See  note  2.)  Dry  in  air 
oven  and  ignite  in  a  weighed  porcelain  crucible  until  the  filter 
paper  is  charred.  Cool.  Add  a  few  drops  of  cone,  nitric 
acid  to  moisten,  then  add  5  c.c.  fuming  nitric  acid  and  warm 
until  sulphur  is  expelled,  then  add  about  5  c.c.  dilute  sul- 
phuric acid  (1  part  acid,  3  parts  water)  and  heat  gently  until 


—  20  — 

nitric  acid  is  driven  off  and  white  fumes  of  sulphuric  acid 
appear.  Now  place  on  triangle  and  heat  gently  until  the  acid 
is  entirely  gone,  then  at  a  low  red  heat  for  a  few  moments, 
cool  and  weigh  as  sulphate  of  lead  (PbSO4.) 

Zinc  Oxide. — Boil  the  filtrate  from  the  lead  precipitation 
to  expel  sulphuretted  hydrogen,  add  a  little  chloride  of 
ammonium,  then  ammonia  to  slight  alkaline  reaction,  then 
colorless  or  slightly  yellow  ammonium  sulphide  in  slight 
excess.  Dilute  to  250  or  300  c.c.,  cover  and  allow  to  stand  in 
a  warm  place  until  settled.  Filter,  Busing  a  good  sized  filter 
paper  and  wash  with  water  containing  a  little  ammonium 
sulphide.  (The  slimy  precipitate  of  zinc  sulphide  has  a 
tendency  to  run  through  the  paper.  This  may  be  greatly 
obviated  by  first  pouring  on  the  filter  a  solution  of  ammonium 
chloride.  Jt  is  a  good  plan  to  change  the  beaker  just  before 
adding  the  precipitate  so  that  should  it  run  through,  time 
will  be  saved  from  refiltering. )  It  is  best  to  wash  by  decan- 
tation  if  the  precipitate  settles  perfectly  clear.  When  the 
precipitate  is  all  on  the  filter  paper  and  the  wash  water  runs 
through,  transfer  the  paper  and  contents  to  a  small  beaker 
and  cover  the  precipitate  with  dilute  hydrochloric  acid,  stand 
in  a  warm  place  until  the  smell  of  hydrogen  sulphide,  is  gone, 
then  heat  gently  and  filter,  washing  the  filter  with  hot 
water.  The  zinc  is  then  precipitated  as  carbonate.  Add  dry 
c.p.  sodium  carbonate  from  the  end  of  a  spatula  (keeping 
beaker  covered  with  a  watch  glass  during  effervesence)  until 
the  zinc  is  precipitated  and  the  sodium  carbonate  is  in  excess. 
Add  about  250  c.c.  hot  water  and  boil  vigorously  for  about 
eight  minutes,  stirring  occasionally  to  prevent  bumping 
which  is  liable  to  occur  before  the  boiling  point  is  reached. 
The  boiling  renders  the  precipitate  less  flocculent  and  makes 
it  settle  much  more  readily.  When  the  precipitate  of  zinc 
carbonate  is  thoroughly  settled,  pour  off  the  clear  supernatant 
liquid,  and  add  to  the  precipitate  about  200  c.c.  more  of  hot 
water  and  stir  vigorously.  Allow  to  settle  again  and  decant 
as  before.  After  several  decantings,  pour  the  precipitate  on 
a  filter  paper,  and  then  rub  the  beaker  clean  with  a  rubber 
tipped  rod  and  wash  with  water  until  the  filtrate  shows  no 
alkaline  reaction  to  test  paper.  The  precipitate  is  then  dried 
in  the  air  oven  and  removed  as  free  as  possible  from  the  paper 


-  21  — 

and  placed  on  glazed  paper.  Ignite  the  paper  in  a  weighed 
porcelain  crucible  and  cool.  Now  add  the  precipitate  and 
ignite  gently  at  first  and  then  at  a  red  heat  to  constant  weight. 
The  carbonate  is  converted  by  the  heat  to  the  oxide  (ZnO) 
and  as  such  is  weighed. 

Sulphuric  Add. — One  gram  is  dissolved  in  a  mixture  of 
10  c.c.  strong  hydrochloric  acid  and  10  c.c.  water  and  boiled 
until  solution  is  complete.  Filter  off  any  insoluble  matter, 
wash  with  hot  water  until  all  lead  chloride  crystals  are  dis- 
solved. Keep  solution  hot,  and  add  barium  chloride  until  a 
precipitate  ceases  to  form  and  stand  in  a  warm  place  to  settle. 
When  completely  settled,  filter,  keeping  solution  hot  and 
wash  with  hot  water  until  a  drop  of  the  filtrate  fails  to  give  a 
turbidity  to  a  solution  of  silver  nitrate.  Ignite  as  in  whiting 
and  convert  to  sulphuric  acid  (SO3)  by  multiplying  by  .3433. 

Calculation. — Assuming  that  all  the  sulphuric  acid  will 
combine  first  with  the  lead,  multiply  the  sulphuric  acid  (SO3) 
found  by  3.78  which  gives  lead  sulphate.  Deduct  from  total 
lead  sulphate  and  if  any  lead  sulphate  remains,  calculate  to 
lead  oxide  (PbO)  by  multiplying  by  .7359.  All  the  zinc  then 
remains  as  zinc  oxide  in  which  form  it  is  weighed.  If,  how- 
ever, there  is  not  enough  lead  to  combine  with  all  the  sul- 
phuric acid  the  remaining  sulphuric  acid  is  calculated  to  sul- 
phate of  zinc  (ZnSOi)  by  multiplying  by  2.01.  Calculate  the 
sulphate  of  zinc  to  zinc  oxide  by  multiplying  by  .503  and  de- 
duct from  total  zinc  oxide.  The  difference  is  the  zinc  oxide 
in  sample. 

Note  1. — Care  must  be  taken  that  lead  sulphate  is  not 
mistaken  for  silica  or  clay,  as  it  is  not  readily  soluble  in 
hydrochloric  acid.  Hard  boiling  will  generally  dissolve  it. 
Should  there  be  any  doubt  about  the  insoluble  matter,  pour 
on  the  filter  a  warm  solution  of  ammonium  acetate,  wash  well 
with  hot  water  acidify  the  filtrate,  then  precipitate  the  lead 
with  sulphuretted  hydrogen,  and  proceed  as  detailed  for  the 
lead  estimation. 

Note  2.— If.  the  precipitate  is  light  colored  it  may  be  due 
to  some  zinc  having  precipitated  or  possibly  free  sulphur, 
due  to  the  solution  being  too  acid.  In  such  cases  the  precip- 
itate is  filtered,  washed  from  filter  and  boiled  with  a  little 
dilute  nitric  acid,  filtered,  washed  with  hot  water  and  the  lead 


-  22  - 

again  precipitated,  after  neutralizing  the  excess  of  acid  with 
ammonia. 

Note  3. — The  sulphide  of  zinc,  after  drying,  may  be 
placed  in  a  weighed  porcelain  crucible  and  ignited  for  some 
time  at  a  red  heat,  allowing  free  access  of  air.  The  sulphide 
is  "roasted"  or  converted  to  the  oxide  at  once.  Care  must  be 
taken  to  heat  long  enough  to  thoroughly  convert  it  to  the 
oxide,  and  several  weighings  should  be  made  to  insure  a  con- 
stant weight.  This  method  is  best  when  the  zinc  is  present 
in  small  amounts. 

Remarks. — In  the  majority  of  cases,  it  is  generally  de- 
sired to  obtain  the  percentages  of  zinc  (as  zinc  oxide)  and 
total  lead  (as  lead  sulphate)  not  regarding  the  probable 
small  amounts  of  lead  oxide  or  zinc  sulphate.  In  the  best 
brands  of  zinc  white,  the  two  latter  compounds  need  not  be 
seriously  considered,  in  fact,  the  problem  of  forming  com- 
binations of  sulphuric  acid,  lead  and  zinc  to  give  oxide  and 
sulphate  of  zinc  and  oxide  and  sulphate  of  lead  is  a  difficult 
one.  But  there  are  on  the  market  pigments  consisting  of 
nearly  equal  parts  of  sulphate  of  lead  and  zinc  oxide  with 
several  percentages  of  lead  oxide  and  zinc  sulphate,  being  the 
resulting  product  from  roasting,  volitilizing  and  condensing 
lead  and  zinc  ores  consisting  largely  of  sulphurets  of  these 
metals. 

As  sulphate  of  zinc  is  soluble  in  water,  a  quick  test  might 
be  proposed  by  leaching  it  out  and  then  estimating  the  zinc 
in  solution,  but  as  zinc  oxide  is  not  absolutely  insoluble  in 
water  a  large  excess  must  be  avoided.  Take  5  grams  and 
brush  into  a  filter  and  then  fill  the  paper  twice  with  warm 
water,  using  about  20  c.c.  for  each  washing.  Allow  all  water 
to  drain  and  then  precipitate  the  zinc  in  the  filtrate  with  sul- 
phuretted hydrogen  after  first  making  acid  with  acetic  acid. 
Proceed  now  as  in  the  estimation  of  zinc  by  "roasting" 
(note  3.)  the  sulphide  to  oxide  and  multiplying  the  zinc  oxide 
by  1.987  to  obtain  the  sulphate  of  zinc,  and  this  result  is  mul- 
tiplied by  100  and  divided  by  5  to  get  the  percentage.  In 
some  instances,  this  method  agrees  very  well  with  the  long 
method  detailed  in  the  first  part,  but  its  usefulness  can  best 
be  applied  in  a  rough  comparison  when  a  number  of  samples 
are  tested  for  "soluble  zinc  compounds." 


—  23  — 

Rapid  Method  for  Analysis  of  Zinc  Oxide. — A  method 
that  is  more  rapid  than  the  tedious  precipitation  of  zinc  as 
sulphide  and  quite  accurate  is  the  following: 

Insoluble  Matter. — Dissolve  one  gram  in  7  c.c.  cone, 
hydrochloric  acid  and  about  10  c.c.  water,  boil  for  ten  minutes. 
After  any  insoluble  matter  is  settled,  filter  and  wash  filter 
with  hot  water.  Dry,  ignite  and  weigh  insoluble  matter. 

Lead. — To  the  filtrate  cautiously  add  about  3  c.c.  cone, 
sulphuric  acid,  (or  until  lead  ceases  to  precipitate)  stir,  evap- 
orate to  white  sulphuric  acid  fumes.  Cool.  Add  10  to  20  c.c. 
water,  stir  to  dissolve  the  zinc  sulphate  and  allow  to  stand 
until  the  lead  sulphate  is  completely  settled.  Then  filter  on 
Gooch  crucible  wash  first  with  water  containing  2%  sulphuric 
acid  then  after  removing  the  filtrate  to  a  beaker  rinsing  out 
the  flask  several  times  with  water,  finish  the  washing  with  a 
mixture  of  half  alcohol  and  half  water.  Dry,  ignite  and 
weigh  lead  sulphate. 

Zinc  Oxide. — To  the  filtrate  in  beaker  containing  the 
zinc  sulphate  add  sodium  carbonate  in  excess,  boil,  filter  and 
wash  with  hot  water,  following  the  direction  given  on  page  20 
for  estimating  the  zinc  oxide. 

Sulphuric  Acid. — For  the  sulphuric  acid  proceed  as 
directed  on  page  21.  Having  now  the  percentage  of  zinc, 
lead  and  sulphuric  acid  the  calculations  are  made  as  indi- 
cated on  page  21. 

ANALYSIS.  OF  ZINC  PIGMENTS  BY  THE  AUTHOR. 

Zinc  Zinc  Zinc 


Zinc  Oxide  

White. 

.     82.84 

White 
96.00 

White 
93.23 

White 
93.23 

Lead  Sulphate  

15.57 

3.57 

4.81 

4.81 

1.60 

Lead  Oxide      

1.96 

100.01 

99.57 

98.04 

100.00 

"Leaded         Zinc  Zinc 

Zinc."          Lead  Lead 

ZincOxide 54.51  52.10 

Lead  Sulphate 34.56          40.51  41.03 

ZincSulphate 1.16  5.12 

Lead  Ozide 

96.18  98.85 


—  24  — 

p.  White  Lead  (Basic  Carbonate  of  Lead. )— The  actual 
composition  of  white  lead  varies  somewhat  from  that  of  theory, 
and  any  material  variance  is  supposed  to  affect  its  value  as  a 
pigment 

The  theoretical  composition  is: 

Lead  Carbonate  (PbCO3) 68.95  per  cent. 

Lead  Hydroxide  (PbH2O2) 31.05    "      " 

100.00    "      " 
or 

Lead  Monoxide  (PbO) 86.32  per  cent. 

Carbonic  Acid  (CO2) 11.36    "      " 

Water  (H2O) 2.32    "      " 


100.00    "      " 

having,  therefore,  the  formula  2PbCO3PbH2O3.  The  function 
of  the  lead  carbonate  seems  to  be  to  impart  body  and  color, 
while  that  of  the  hydrate  of  lead  is  to  form  a  chemical  com- 
bination with  the  oil  to  greatly  increase  the  covering  pro- 
perties. 

In  the  analysis  of  white  lead  the  carbonic  acid  is  the 
usual  constituent  sought,  and  its  determination  is  one  requir- 
ing care  and  exactness  of  apparatus.  The  usual  method  is  to 
calculate  the  carbonic  acid  to  lead  carbonate,  substract  from 
100,  and  express  the  difference  as  lead  hydrate.  The  reason 
for  this  is  that  the  estimation  of  the  combined  water  requires 
heat  to  drive  it  off  and  the  liability  of  the  sample  to  contain 
carbonaceous  compounds  such  as  lead  acetate,  traces  of  oil, 
etc.  would  give  erroneous  results. 

In  some  laboratories,  however,  the  combustion  method  is 
used,  as  it  gives  quick  and  approximate  results  of  sufficient 
accuracy  to  check  purchases  and  guard  against  adulterating 
and  for  this  reason  the  method  is  detailed  on  page  28. 

If  only  the  lead  is  desired,  it  may  be  obtained  as  follows: 

Dissolve  1  gram  in  5  c.c.  nitric  acid  (1 42  sp.  gr. )  and  20  c.c. 
water  and  heat  to  solution.  If  any  insoluble  matter  appears, 
filter  and  wash  with  hot  water.  Now  add  dilute  sulphuric  acid 
to  filtrate,  a  few  drops  at  a  time,  with  constant  stirring,  until 
the  white  precipitate  of  lead  sulphate  ceases  to  form,  and 
evaporate  in  hot  plate  to  sulphuric  acid  fumes.  Cool.  Add 
cautiously  15  c.c.  water  and  an  equal  bulk  of  alcohol,  stir 


—  25  — 

thoroughly  and  allow  to  stand  about  an  hour,  or  until  super- 
natant liquid  is  perfectly  clear.  Filter  in  a  weighed  Gooch 
crucible.  Wash  with  a  mixture  of  one  half  water  and 
one  half  alcohol.  After  four  or  five  washings,  suck  dry, 
remove  crucible,  attach  cap,  and  place  on  a  hot  plate  for  a 
few  moments  to  dry,  then  ignite  on  triangle  at  a  red  heat  for 
five  minutes.  Cool  and  weigh.  Multiply  weight  of  lead 
sulphate  by  factor  .7359  which  converts  it  to  (PbO)  lead  oxide. 

If  for  any  reason  the  Gooch  crucible  is  not  at  hand  or 
inadmissable,  and  the  lead  sulphate  must  be  filtered  on  paper, 
proceed  as  detailed  above  and  wash  the  paper,  after  adding 
the  precipitate,  with  the  mixture  of  alcohol  and  water.  Then 
dry  in  oven,  remove  the  lead  sulphate  from  the  paper  as  clean 
as  possible,  placing  in  a  large  water  glass,  and  ignite  paper  in 
a  weighed  porcelain  crucible.  When  all  the  carbon  is  burnt 
off,  cool  the  crucible,  then  add  3  or  4  c.c.  water  and  about  two 
drops  of  nitric  acid  (sp.  gr.  1.42),  and  warn  until  all  the 
metallic  lead  is  in  solution.  Cool  and  add  a  few  c.c.  dilute 
sulphuric  acid  to  precipitate  the  dissolved  lead  then  evaporate 
on  water  bath  until  no  more  water  or  nitric  acid  fumes  are  given 
off.  This  may  be  done  more  rapidly  by  placing  in  the  warm 
part  of  a  hot  plate  but  care  must  be  observed  that  none  of 
the  contents  spirts  out.  Now  place  crucible  in  triangle  and 
heat  by  playing  the  flame  gently,  and  when  all  the  sulphuric 
acid  is  expelled  heat  at  a  red  heat  for  a  few  minutes,  and  cool. 
Add  the  bulk  of  the  precipitate  and  .again  heat  to  redness  for 
about  5  minutes.  Cool  and  weigh. 

F.  C.  A.  Meisel  (School  of  Mines  Quar.  1.04,  Vol.  XIV.)  has  given 
the  result  of  an  investigation  for  the  estimation  of  water  and  carbonic 
acid  in  white  leads  by  four  methods:  viz.,  Loss  in  ignition,  loss  by  use  of 
alkalimeter,  measuring  carbonic  acid  gas  by  volume,  and  absorption  of 
carbonic  acid  in  caustic  potash  solution,  reaching  the  conclusion  that 
the  last  method  gives  the  most  trustworthy  results,  although  it  possibly 
requires  longer  time. 

Estimation  of  Carbonic  Acid. — The  carbonic  acid  is 
absorbed  in  the  Liebig  potash  bulb  A,  which  carries  the 
calcium  chloride  tube  to  prevent  any  moisture  from  being 
absorbed  from  the  aspirator.  Connecting  with  the  Liebig 
bulbs  are  two  U  tubes,  D,  D,  in  which  is  freshly  made 
anhydrous  sulphate  of  copper  and  pumice  for  the  absorption 
of  any  traces  of  hydrochloric  acid  gas  and  moisture.  H  is  a 


—  26  — 

boiling  flask  with  a  capacity  of  150  c.c.,  fitted  with  a  rubber 
stopper  with  two  holes  in  one  of  which  passes  the  end  of  a 
glass  condenser  and  through  the  other  passes  the  bent  glass 
tube  of  the  bulb  I.  The  latter  has  a  glass  stop  cock  at  K. 
J  is  a  wash  bottle  containing  solution  of  caustic  potash.  The 
connection  at  L  is  made  with  a  rubber  stopper  which  fits 
tightly  into  the  bulb  I.  M.  is  a  rubber  tube  connecting  the 
aspirator. 

The  caustic  potash  solution  should  h^ve  a  specific  gravity 
of  about  1.27.  This  may  be  made  by  dissolving  30  grams  of 
the  stick  potash  in  100  c.c.  water,  which  will  make  a  solution 
of  the  desired  strength. 

The  calcium  chloride  should  be  dried  thoroughly  at 
200  c.c.  (not  fuzed);  the  white  porous  anhydrous  chloride 
thus  produced  being  very  deliquescent  it  should  be  kept  in 
glass  stoppered  bottle.  The  copper  sulphate  and  pumice  are 
prepared  by  heating  pieces  of  each,  which  should  be  about 
the  size  of  a  pea,  in  a  porcelain  dish  until  the  blue  crystals 
are  white,  then  transferred  to  a  glass- stoppered  bottle  for 
keeping. 

For  the  estimation  of  carbonic  acid  gas  (CO2),  one  gram 
of  the  sample  is  carefully  brushed  into  H  and  after  the  Lie- 
big  bulbs  are  weighed  the  apparatus  is  connected,  the  water 
started  in  condenser  E  and  the  glass  stop  cock  K  in  bulb  I 
closed.  Pour  in  bulb  tube  I  diluted  hydrochloric  acid  made 
up  of  15  c.c.  hydrochloric  acid  (12  sp.  gr.)  and  40  c.c.  water. 
Insert  the  rubber  stopper  L  securely  in  bulb  I  and  open  the 
stop  cock  K  so  that  the  acid  will  flow  elowly  in  H.  When 
nearly  all  the  acid  has  passed  into  flask  H  close  stop  cock  and 
apply  a  slow  heat  increasing  gradually  until  the  solution  boils 
which  will  take  about  10  minutes.  A  few  moments  further 
boiling  will  bring  aJl  the  lead  chloride  in  solution.  When 
this  is  accomplished  the  flame  is  lowered  and  suction  com- 
menced. After  10  minutes  the  flama  is  withdrawn  and  the 
suction  continued  at  the  rate  of  about  three  bubbles  per 
second  for  about  20  minutes,  at  which  time  the  apparatus 
should  be  free  from  CO2. 

Disconnect  the  potash  bulbs  and  place  in  the  balance 
case  for  about  30  minutes  to  get  the  same  temperature  as  that 
of  the  case.  At  the  end  of  this  time  if  the  levels  of  the 


—  27  — 


—  28  — 

potash  solutions  are  not  the  same  remove  the  end  caps  to 
equalize  the  pressure,  then  replace  and  weigh.  The  increase 
in  weight  is  the  amount  of  CO2,  which,  multiplied  by  100, 
gives  the  percentage.  This,  multiplied  by  the  factor  6.068, 
gives  the  percentage  of  carbonate  of  lead  and  the  difference 
between  this  and  100  is  expressed  as  hydrate  of  lead. 

With  due  regard  to  the  necessary  precautions,  the  foregoing  method 
for  the  estimation  of  carbonic  acid  is  accurate.  The  apparatus  should 
always  be  tested  by  running  a  blank,  boiling  the  dilute  hydrochloric 
acid  solution  (but  of  course  omitting  the  sample)  for  10  minutes,  and 
aspirating  about  twenty  minutes.  The  Liebig  bulb  should  show  no 
appreciable  increase  in  weight. 

Combustion  method  for  the  determination  of  lead  oxide,  car- 
bonic acid  and  water  in  dry  basic  carbonate  of  lead. 

The  method  consists  of  heating  the  sample  contained  in  a 
platinum  boat,  in  a  short  glass  tube  thus  decomposing  it  into 
water,  carbonic  acid  gas  and  litharge  (oxide  of  lead).  The 
litharge  remains  in  the  platinum  boat,  while  the  carbonic 
acid  gas  is  absorbed  in  a  solution  of  caustic  potash  in  a  Lie- 
big  absorption  bulb,  and  the  water  is  taken  up  in  a  TJ  tube 
containing  granulated  calcium  chloride.  Having  the  weights 
of  litharge  carbonic  acid  and  water  the  several  percentages 
are  calculated. 

The  apparatus  is  supported  by  the  wooden  stand.  B  is 
a  piece  of  heavy  glass  combustion  tubing  about  six  inches 
long  and  sufficient  diameter  (f  inch  inside)  to  admit  the 
platinum  boat  A.  At  the  right  hand  end  is  a  rubber  tube 
which  fits  snugly  to  the  calcium  chloride  tube  C.  On  the 
left  hand  side  is  inserted  a  rubber  stopper,  through  which 
passes  a  small  glass  tube  to  connect  the  guard  tube  Y  which 
is  also  filled  with  calcium  chloride. 

The  platinum  boat  A  is  a  small  narrow  box  which  must 
hold  one  gram  of  the  sample  to  be  examined.  C  is  the  U 
tube  containing  dried  granulated  calcium  chloride  to  absorb 
the  moisture,  and  D  is  the  Liebig  potash  bulbs  containing  a 
solution  of  caustic  potash  in  water,  sp.  gr.  1.2  for  the  absorp- 
tion of  carbonic  acid  gas.  Z  is  another  chloride  of  calcium 
tube  similar  to  C,  but  is  not  weighed  and  is  a  guard  to  pre- 
vent any  moisture  getting  back  into  D  or  C.  As  explained 
before  Y  is  a  calcium  chloride  tube  to  dry  the  atmospheric  air 


before  entering  the  com- 
bustion tube,  and  X  is  a 
small  bottle  containing  a 
strong  solution  of  potash 
to  free  the  air  from  car- 
bonic acid.  W  is  a  rub- 
ber tube  connecting  the 
aspirator  bottle  to  draw 
air  through  the  appara- 
tus. All  chloride  of  cal- 
cium tubes  should  have  a 
plug  of  cotton  at  the  ends 
to  prevent  any  of  the  chlo- 
ride from  being  carried 
out. 

Detach  C  and  D  and 
wipe  carefully  with  dry 
cloth.  Both  ends  of  each 
should  be  carefully  closed 
by  small  pieces  of  solid 
glass  tubes  inserted  in  the 
pieces  of  rubber  tubing. 
Next  weigh.  Then  weigh 
the  platinum  boat  and 
in  it  weigh  one  gram  of 
the  sample.  Detach  com- 
bustion tube  and  gently 
heat  over  a  naked  flame 
until  the  tube  is  hot,  then 
suck  the  air  through  by 
the  mouth  —  this  being 
necessary  to  remove  any 
moisture.  Now  connect 
the  whole  apparatus  in 
the  position  as  seen  in  the 
cut.  Draw  air  through 
by  means  of  the  aspirator 
bottles  at  the  rate  of  a 
few  bubbles  per  second. 
Note  whether  there  are 


-  30- 

any  leaks,  and  if  there  are  none,  heat  with  the  alcohol  lamp 
slowly  along  the  bottom  of  the  tube  until  the  whole  tube  is 
hot  Place  the  lamp  underneath  boat  and  heat  for  about  20 
minutes  or  until  the  lead  has  changed  from  white  to  the 
red  color  of  litharge.  When  it  is  of  uniform  color  remove 
the  lamp  and  allow  air  to  aspirate  for  about  10  minutes. 
Disconnect  the  calcium  chloride  tube  C,  plug  the  ends  as 
before  the  operation,  and  do  the  same  with  the  potash  bulbs 
D  and  weigh.  Observe  precautions  on  p.  26,  for  weighing 
the  bulbs.  The  increase  of  weight  equals  the  amounts  of 
carbonic  acid  and  water.  When  these  are  weighed  the  boat 
containing  litharge  will  be  cool  enough  to  weigh.  The 
difference  between  the  weight  of  the  boat  plus  litharge  and 
the  weight  of  boat  equals  the  weight  of  litharge.  We  now 
have  the  following  weights:  Litharge  (PbO),  water  (H2O), 
carbonic  acid  gas  (CO2). 


—  31  — 

Qualitative  Tests  of  White  or  Tinted  Mixed  Paints,  Paste 
Paints,  Fillers,  Etc. 

The  readiness  of  lead  sulphate  and  calcium  carbonate  to 
react,  when  the  latter  is  in  excess,  in  treatment  with  dilute 
acetic  acid  precludes  the  use  of  acetic  acid  as  a  general  sol- 
vent for  mixtures  of  pigments. 

When  the  above  mentioned  pigments  are  so  treated,  lead 
carbonate  and  calcium  sulphate  are  formed  and  both  go  into 
solution  and  part  if  not  all  of  the  lead  existing  as  sulphate 
will  be  figured  with  the  soluble  lead  pigments  such  as  lead 
oxide  or  carbonate. 

Acetic  acid  may  be  used,  however,  when  either  one  of 
them  only  is  present  and  although  lead  sulphate  is  slightly 
soluble  the  result  will  be  accurate  enough  (especially  enough 
when  sulphuric  acid  is  also  estimated)  for  the  purposes  for 
which  an  analysis  of  a  mixtures  of  pigments  is  used. 

As  there  are  on  the  market,  and  in  large  use,  pigments 
that  contain  considerable  lead  sulphate  such  as  "sublimed 
lead,"  "leaded  zinc,"  "zinc  lead,"  "zinc  oxide,"  it  is  obvious 
that  acetic  acid  as  a  solvent  cannot  be  used  to  advantage 
except  in  the  mixtures  in  which  lead  sulphate  and  calcium 
pigments  are  present  either  singly  or  not  at  all. 

For  this  reason  it  will  be  necessary  to  vary  the  method 
employed  in  accordance  with  preliminary  tests. 

Of  course  the  regular  methods  of  analysis  may  be  used  in  a  mixture 
of  pigments  by  estimating  the  acid  radicals  and  bases,  but  the  time  in- 
volved is  much  longer  and  the  tedious  separation  of  lead  and  zinc  by  the 
use  of  sulphuretted  hydrogen  and  ammonium  sulphide  in  mineral  acid 
solution  is  avoided.  Then,  too,  the  combinations  to  arrive  at  the  differ- 
ent pigments  used  is  often  a  matter  of  conjecture.  In  the  foregoing  the 
combinations  are  much  more  rapidly  obtained  particularly  in  scheme  I. 


CHAPTER  III. 


WHITE  AND  TINTED  PAINTS. 

Qualitative  Analysis  of  White  or  Tinted  Paints,  Paste 
Paints,  Fillers  and  Enamel  Paints. 

Boil  about  one  gram  of  the  extracted  sample  with  from 
25  c.c.  to  50  c.c.  of  acid  ammonium  acetate  (see  note  1)  for  15 
minutes.    Filter  and  wash  with  hot  water.     Note  whether 
effervescence  takes  place,  indicating  carbonates. 
KESIDUE. 

Ignite  residue  in  a  porcelain  crucible.  When  cool  test  portion 
by  flame  test  for  barytes.  If  siiica  or  China  clay  is  suspected  mix 
residue  with  five  or  six  times  its  weight  of  sodium  carbonate  in  a 
platinum  crucible.  Fuse.  When  cool  place  crucible  and  contents  in 
beaker  and  coyer  the  crucible  with  water  and  boil  until  the  mass  is  dis- 
integrated. Filter.  Dissolve  the  barium  carbonate  on  filter  in  few  c.c. 
hydrochloric  acid  and  allow  to  run  in  another  beaker.  Then  add 
sulphuric  acid  in  slight  excess  which  will  throw  down  any  barium  as 
barium  sulphate.  See  Note  1. 

To  the  nitrate  from  the  barium  carbonate  and  barium  sulphate  add 
hydrochloric  acid  in  slight  excess,  place  in  a  platinum  dish  and  boil 
rapidly  to  dryness  on  a  hot  plate  or  directly  over  a  low  Bunsen  burner 
flame.  Heat  until  hydrochloric  and  sulphuric  acids  are  gone  and  cool. 
Moisten  with  hydrochloric  acid,  add  about  25  c.c.  water  and  warm  to 
dissolve.  Any  insoluble  residue  is  silica.  Filter,  and  to  filtrate  add 
ammonia  in  slight  excess  and  boil.  A  precipitate  of  aluminum  hydrate 
together  with  the  presence  of  silica  indicates  China  clay.  Now  add 
ammonium  oxalate,  stand  a  short  time  and,  if  calcium  oxalate  is  preci- 
pitated, filter.  Cool  filtrate  add  ammonia  and  sodium  phosphate,  and  if 
a  precipitate  of  ammonium-magnesium-phosphate  appears  after  standing 
a  few  hours  it  indicates  presence  of  magnesiiim  silicate.  See  Note  2. 


—  33  — 

FlLTEATE. 

Divide  the  filtrate  in  three  nearly  equal  parts  and  pro- 
ceed in  each  as  follows: 


Test   for  sulphates 

Add  a  few  c.c.  cone. 

Ammonia  is  added 

by  adding  a  few  drops 
of  hydrochloric   acid, 
heat  to  boiling,  then 
add  a  few  c.c.  of  bari- 

sulphuric acid  or  until 
the  addition  of  a  few 
drops  ceases  to  form  a 
precipitate  of  lead  sul- 

in excess,  then  ammo- 
nium sulphide  until  a 
precipitate   ceases  to 
form.    Warm  and  stir 

um  chloride.     A  pre- 

phate.  Filter.   To  the 

to  collect  precipitate. 

cipitate  of  barium  sul- 

filtrate add  ammonia 

Filter.    To  the  warm 

phate    indicates    pre- 

in excess,  then  a  few 

filtrate  add  ammonium 

sence  of  lead  sulphate 
or    possibly    calcium 
sulphate. 

c.  c.    ammonium    sul- 
phide.    A  white  pre- 
cipitate indicates  pre- 

oxalate in  excess,  heat 
to  boiling  point  and 
filter  off  calcium  ox- 

See Note  3. 

sence  of  zinc  oxide. 

alate  indicating   pre- 

See Note  4. 

sence  of  calcium  car- 

bonate or  calcium  sul- 

phate.     Cool  the  fil- 

trate and  add  solution 

of  sodium  phosphate, 

stir  and  stand  in  a  cool 

place  for  about  thirty 

minutes    and   if   any 

magnesium  is  present 

a  precipitate  will  form 

indicating  magnesium 

carbonate. 

See  Note  5. 

Note  1. — Acid  ammonium  acetate  solution  may  be  pre- 
pared by  mixing  15  parts  water  with  30  parts  ammonia  (sp. 
gr.  0.90)  to  which  is  added  50  parts  glacial  acetic  acid.  Test 
the  solution  with  barium  chloride,  which  should  give  no  trace 
of  a  precipitate.  About  70  c.c.  of  this  solution  will  dissolve 
one  gram  of  lead  sulphate  in  boiling  ten  to  fifteen  minutes.  ^ 

Note  2. — If  any  silica,  other  than  that  in  the  clay,  is 
suspected  it  will  be  necessary  to  make  a  quantitative  analysis 
in  order  to  determine  its  percentage. 

Note  3. — Calcium  sulphate  (gypsum)  is  used  in  paints 
to  some  extent  and  its  presence  complicates  an  analysis  when 
whiting  or  lead  compounds  are  present.  It  cannot  be  de- 
tected by  dissolving  the  gypsum  in  water  as  might  at  first 
be  supposed,  owing  to  the  reaction  that  takes  place  between 
sulphates  and  carbonates  of  lead  and  calcium.  The  fact  of 
this  peculiar  reaction  is  brought  out  by  G.  W.  Thompson  in 


—  34  — 

the  "Journal  of  the  Society  of  Chemical  Industry,  Nov.  80, 
1896,"  and  the  method  here  used  for  determining  mixtures  of 
sulphates  and  carbonates  of  lead  and  lime  pigments  by  nitric 
acid  and  alcohol  is  based  on  the  method  given  there.  To 
test  for  the  presence  of  gypsum  proceed  as  follows:  To 
about  1  gram  add  20  c.c.  of  a  mixture  of  9  parts  alcohol  (95%  } 
and  1  part  nitric  acid  (1.42  sp.  gr.)  and  after  stirring  allow  to 
stand  about  20  minutes.  Then  decant  on  a  filter  and  again 
treat  with  the  nitric  acid-alcohol  mixture,  allowing  to  stand  and 
decant  as  before.  Repeat  the  treatment  four  times  then  pour 
any  residue  on  filter  and  wash  residue  with  nitric  acid-alcohol 
mixture.  If  gypsum  was  present  it  will  remain  undissolved, 
while  only  the  calcium  carbonate  (with  possibly  some  of  the 
zinc  and  lead  salts)  will  go  into  solution.  Now  wash  the 
residue  of  gypsum  and  other  insoluble  matter  into  a  beaker 
with  the  aid  of  a  wash  bottle,  add  a  few  c.c.  hydrochloric  acid, 
boil  and  filter.  To  the  filtrate  add  ammonia  in  slight  excess, 
then  ammonium  sulphide,  and  warm  until  precipitate  is  set- 
tled. Filter.  To  the  warm  filtrate  add  ammonium  oxalate 
and  warm  a  few  moments.  A  white  precipitate  of  calcium 
oxalate  indicates  the  presence  of  calcium  which  existed  as 
sulphate. 

Note  4.  —  If  lead  is  present  it  may  be  as  the  basic 
carbonate,  lead  sulphate  or  lead  oxide.  Only  a  complete 
quantitative  analysis  will  distinguish  in  which  form  the  lead 
may  be. 

Note  5. — If  only  traces  of  magnesium  carbonate  are 
found  they  are  probably  due  to  impurities  in  the  whiting.  It 
is  sometimes  used  in  woodfillers. 

Note  6. — Zinc  sulphite  and  lead  sulphite  are  seldom  if 
ever  found  in  American  paints  and  for  this  reason  have  not 
been  considered  herein. 


—  35  — 


Having  now  the  qualitative  tests  the  scheme  to  use  is 
determined  by  the  following  conditions: 

USE  SCHEME  I. 

If  sulphates  are  present  but  no  calcium  pigments. 
(Indicating  sulphate  of  lead  and  absence  of  calcium  car- 
bonate or  calcium  sulphate.) 

Or,  if  calcium  pigments  are  present  but  no  sulphates. 

(Indicating  calcium  carbonate  and  absence  of  calcium 

sulphate  and  lead  sulphate.) 

USE  SCHEME  II. 

"When  sulphates  and  calcium  pigments  are  present. 

NOTE.— The  above  does  not  include  the  insoluble  pigment,  barytea. 


—  36  — 

A  Gooch  crucible  is  quite  indispensable  for  the  rapid  filtering  and 
ignition  of  precipitates,  and  is  particularly  useful  in  igniting  precipitates 
that  are  liable  to  be  reduced  by  filter  paper,  such  as  lead  sulphate.  The 
asbestos  of  the  silky,  fibrous  kind  should  be  previously  digested  for 
several  hours  in  dilute  hydrochloric  acid,  then  washed  by  decantation 
with  distilled  water  until  free  from  acid,  and  thrown  on  a  filter  to  drain 
and  dry,  then  kept  in  a  wide  mouth  bottle.  To  prepare  the  asbestos  pad 
in  the  Gooch  crucible,  mix  several  grams  (or  a  good  sized  "pinch")  in  a 
small  beaker  with  distilled  water  and  pour  in  crucible  applying  gentle 
suction.  When  quite  dry  by  means  of  the  finger  press  down  the  edge  of 
the  asbestos  so  that  the  whole  pad  has  an  even  surface  and  is  about  an 
eighth  of  an  inch  in  thickness.  Now  apply  pressure  until  quite  free 
from  water,  remove  from  funnel,  attach  the  platinum  cap  and  place  on 
hot  plate  to  dry,  then  place  on  triangle  and  ignite  for  about  five  minutes 
over  flame  at  red  heat.  Cool,  remove  cap  and  weigh. 

If  for  any  reason  the  Gooch  crucible  is  not  admissible  and  it  is  de- 
sired to  use  a  paper  filter  in  preference  to  the  asbestos  pad,  a  perforated 
platinum  cone  may  be  used  to  prevent  the  paper  being  broken  by  the 
pressure  of  the  pump.  A  funnel  should  be  selected  that  the  cone 
exactly  fits  so  that  the  paper  will  not  be  broken  from  the  sharp  edge. 
Fold  the  paper  and  place  in  funnel,  then  fill  the  funnel  with  water  and 
apply  the  suction.  The  paper  will  then  be  drawn  tightly  to  the  cone 
and  funnel  and  is  ready  for  use.  The  use  of  filter  pumps  to  facilitate 
filtering  operations  has  now  become  quite  general  and  in  most  labora- 
tories are  indispensable.  The  kind  of  pump  is  generally  determined  by 
the  water  supply.  The  Richards  injector  is  generally  used  where  the 
water  supply  is  sufficient.  A  very  serviceable  and  simple  pump  may  be 
arranged  by  using  aspirater  bottles  as  shown  in  cut  on  p.  37.  The  aspi- 
rate r  bottles  A  and  B  connect  by  B  eans  of  a  rubber  tube  with  C  which  is 
an  empty  guard  flask.  It  is  necessary  that  the  fall  of  water  between  A  and 
B  should  be  a  considerable  distance,  about  seven  feet  being  generally 
sufficient.  On  the  tube  connecting  A  and  B  is  a  clamp  for  regulating 
the  flow.  The  guard  flask  C  is  connected  by  another  rubber  tube  with 
flask  E.  In  the  neck  of  E  is  a  funnel  for  holding  either  the  platinum 
cone  or  crucible.  The  water  flowing  from  A  to  B  causes  a  partial 
vacuum  and  creates  a  pressure  on  the  filter.  As  soon  as  the  water  has 
run  from  A  to  B  they  are  quickly  reversed  and  the  flow  resumed,  the 
same  water  being  used  over  again.  It  is  obvious  that  for  filtering  corro- 
sive liquids  such  as  nitric  acid,  this  method  cannot  be  used  to  advan- 
tage, but  for  lead  sulphate  in  sulphuric  acid  or  zinc  carbonate,  etc.,  it 
will  be  found  very  serviceable. 


—  37  — 


28S46Q 


—  38  — 

2.    SCHEME  I. 

Boil  one  gram  of  the  sample  in  5  c.c.  glacial  acetic  acid 
and  about  25  c.c.  of  water  for  10  minutes.    Wash  down  the 
sides  of  the  beaker  with  water,  then  dilute  to  about  50  c.c. 
and  stand  until  settled.    Filter  on  a  9  c.m.  filter. 
EESIDUE. 

The  residue  insoluble  in  acetic  acid  may  consist  of  either  lead  sul- 
phate, china  clay,  barium  sulphate,  silica  or  magnesium  silicate. 

In  order  to  effect  a  decomposition  and  solution  it  will  be  necessary 
to  fuse  in  a  platinum  crucible  which  is  impracticable  when  lead  sulphate 
is  present.  To  remove  the  lead  sulphate  either  one  of  two  methods  may 


1.— By  converting  to  lead  carbonate  and  dissolving  in  dilute  acid  p.  39. 
2.— Dissolving  at  once  in  hot  ammonium  acetate  p.  39. 
In  either  case  the  insoluble  clay,  silica,  barytes,  magnesium  silicate 
will  remain  to  be  treated  as  directed  on  p.  40. 

FILTRATE. 

Lead  acetate  Pb  (CaHsO^,  Zinc  acetate  Zn  (C2H3O2)2,  Calcium  acet- 
ate Ca  (C-sHsOj^,  Magnesium  acetate  Mg  (C2H3O2)2. 

Pass  a  rapid  stream  of  sulphuretted  hydrogen  gas  until  saturated, 
warm  and  allow  the  precipitates  of  lead  and  zinc  sulphides  to  settle 
quite  well.  Filter  on  a  double  filter  using  a  platinum  cone  and  pump, 
and  when  the  supernatant  liquid  is  filtered  add  about  20  c.c.  sul- 
phuretted hydrogen  water.  Stir  and  again  allow  the  bulk  of  the  precip- 
itate to  settle.  Filter  and  repeat  the  washing  by  decantation  four  times. 
Now  run  the  precipitate  on  the  paper  and  by  the  aid  of  the  wash  bottle 
containing  sulphuretted  hydrogen  spirt  any  loose  precipitate  on  the 
filter  disregarding  what  adheres  to  the  beaker.  Wash  once  or  twice  on 
filter  with  sulphuretted  hydrogen  water  and  Buck  quite  dry. 


PRECIPITATE. 

Lead  sulphide  (PbS),  Zinc  sul- 
phide (ZnS),  p.  41. 


FILTRATE. 

Calcium  acetate,   Ca 
Magnesium  acetate,  Mg  (C2H3O2)2, 
p.  42. 


-  39  — 


REMOVING  LEAD  SULPHATE  FROM  EESIDUE  INSOLUBLE 
IN  ACETIC  ACID. 


Method  II.— By  Ammon- 
ium Acetate :  Remove  filter 
and  contents  from  funnel, 
place  in  a  beaker  and  add 
from  30  c.c.  to  50  c.c.  acid 
ammoninm  acetate  solution, 
(see  note  I.)  and  boil  for  10 
minutes.  Then  filter  any 
insoluble  residue  (contain- 
ing first  filter  paper)  and 
wash  thoroughly  with  hot 
water.  The  lead  will  now  be 
in  the  filtrate.  The  residue 
is  treated  as  described  on 
p.  40. 


Method  I.— By  Ammonium  Carbon- 
ate :  Plug  up  the  end  of  the  funnel  with 
a  filter  paper  tightly  rolled  or  a  better 
plan  is  to  slip  on  the  end  a  piece  of  rub- 
ber tubing  about  an  inch  long  and  close 
up  the  other  end  of  the  rubber  tube  with 
a  bit  of  solid  glass  rod.  Now  place  on  the 
filter  two  or  three  grams  of  ammonium 
carbonate  and  fill  the  filter  with  warm 
water  within  a  half  inch  of  the  top. 
Cover  with  a  watch  glass  and  allow  to 
stand  in  a  warm  place  for  six  to  ten 
hours— best  over  night.  The  lead  sul- 
phate is  by  this  means  converted  to  lead 
carbonate.  Now  pull  off  the  rubber  plug 
and  wash  the  filter  with  warm  water. 
Reject  filtrate.  Dissolve  the  lead  car- 
bonate by  pouring  warm  acetic  acid  on 
filter  quickly  covering  with  watch  glass 
to  prevent  loss  by  effervescence.  Wash 
off  watch  crystal,  allowing  the  water  to 
run  on  the  filter  and  then  wash  out  the 
lead  acetate  with  hot  water.  It  is  a  good 
plan  to  add  acetic  acid  a  second  time  to 
make  sure  that  all  the  lead  carbonate  is 
dissolved.  Proceed  with  the  residue  as 
described  on  p.  40. 

Determination  of  Lead  in  Solution  obtained  by  either 
Method  I  or  II. — Pass  a  stream  of  sulphuretted  hydrogen 
gas  through  the  solution  until  saturated  and  filter.  Reserve 
filtrate.  If  there  is  considerable  lead  sulphide  proceed  ex- 
actly as  described  on  p.  24  for  the  estimation  of  lead  as  sul- 
phate, using  a  Gooch  crucible.  The  lead  is  weighed  as  sul- 
phate (PbSO4)  and  exists  as  such  in  the  sample.  •  Should  the 
precipitate  of  lead  sulphide  be  small  it  may  be  converted 
directly  to  the  sulphate  as  follows:  Dry  precipitate  in  an 
air  oven  and  carefully  transfer  from  the  paper  to  a  piece  of 
glazed  paper  or  watch  glass.  Now  fold  the  paper  and  place  in 
a  weighed  porcelain  crucible  and  ignite  until  charred.  Add 
the  precipitate  and  moisten  all  with  nitric  acid  (1.42  sp.  gr.) 
Heat  gently  until  the  carbon  is  consumed,  cool  and  add  about 
5  c.c.  fuming  nitric  acid,  cover  with  small  watch  crystal  and 


—  40  — 

heat  until  the  free  sulphur  is  oxidized.  Then  add  a  drop  or 
two  of  sulphuric  acid  and  heat  as  usual,  finally  cooling  and 
weighing  the  lead  sulphate. 

Filtrate. — The  filtrate  from  the  lead  sulphide  precipitate 
is  boiled  to  expel  sulphuretted  hydrogen,  then  ammonia 
added  in  slight  excess  and  ammonium  oxalate.  If  a  precipi- 
tate appears  it  is  probably  due  to  calcium  carbonate  in  the 
china  clay  or  possibly  whiting  that  failed  to  dissolve  in  the 
acetic  acid.  If  the  sample  contains  whiting,  that  found  in  the 
insoluble  residue  is  added  to  it  but  if  no  appreciable  amount 
is  present  it  is  added  to  the  china  clay  or  if  desired  it  reported 
singly.  China  clay  or  silica  of  good  quality  does  not  contain 
calcium  soluble  in  acetic  acid. 

Residue  Insoluble  in  Acetic  Acid  After  Removing  Lead 
Sulphate. — Dry  the  residue  left  after  removing  the  lead  sul- 
phate, clean  precipitate  as  free  as  possible  from  the  paper, 
ignite  paper  in  a  weighed  porcelain  crucible,  cool,  add  preci- 
pitate and  heat  to  redness  for  ten  minutes.  Weight  equals 
barytes,  silica  or  china  clay.  Transfer  to  a  capacious  plat- 
inum crucible,  add  ten  times  its  weight  of  sodium  carbonate, 
fuse  and  proceed  as  directed  in  china  clay  p.  11.  After  the 
mass  is  thoroughly  disintegrated,  filter  off  the  insoluble  bar- 
ium carbonate,  wash  with  hot  water  (reserving  filtrate)  and 
dissolve  on  filter  with  dilute  hydrochloric  acid.  Finally  pre- 
cipitate with  sulphuric  acid  as  directed  on  p.  16,  which  is  the 
barium  sulphate  existing  as  such  in  the  sample. 

If  the  barium  sulphate  be  deducted  from  the  total  insol- 
uble matter  the  difference  is  the  china  clay  and  silica.  If, 
however,  a  more  accurate  result  is  desired  unite  the  filtrates 
from  the  barium  carbonate  and  barium  sulphate  precipita- 
tions transfer  to  a  platinum  dish  evaporate  to  dryness  first  on 
a  water  bath  and  finishing  on  a  hot  plate.  Heat  until  no  more 
sulphuric  acid  fumes  are  given  off.  Cool.  Add  sufficient 
water  and  heat  in  water  bath  until  all  is  in  solution  except  the 
silica,  then  add  a  drop  or  two  of  sulphuric  acid  and  again 
bring  to  dryness  and  heat  until  all  acid  fumes  are  driven  off. 
Now  add  water  and  proceed  as  directed  in  china  clay  p.  11. 
for  the  estimation  of  silica  and  alumina.  The  average  com- 
position of  china  clay  is  2  SiO2,  A12O3  2  H2O  containing  39.53 
per  cent,  of  A12O3.  Multiply  the  A12O3  found  by  2.537  and 


—  41  — 

the  result  will  be  china  clay.  Then  multiply  the  china  clay 
found  by  factor  .465  and  the  result  will  be  the  silica  in  the 
china  clay  and  if  the  difference  exceeds  5  per  cent,  it  may  be 
due  to  free  or  added  silica. 

If  the  qualitative  examination  shows  magnesium  present  in  the  in- 
soluble residue  then  it  will  be  necessary  to  proceed  with  the  filtrate  after 
filtering  off  the  aluminum.  This  is  done  exactly  as  detailed  in  china 
clays  for  the  estimation  of  calcium  and  magnesium.  When  such  com- 
plex insoluble  residues  are  found  and  this  is  rarely  the  case,  it  is  a 
difficult  problem  to  form  an  opinion  or  give  percentage  of  the  original 
products.  In  such  cases  it  is  the  better  plan  to  give  the  percentage 
found  such  as  silica,  aluminum  oxide,  magnesium  oxide,  barytes,  etc., 
with  possibly  an  attempt  to  combine  the  percentages  to  give  probabl* 
products,  which  may  ba  free  silica,  barytes,  china  clay,  magnesium, 
silicate,  etc. 

Precipitate  of  Lead  Sulphide  and  Zinc  Sulphide. — 
Remove  the  filter  and  contents  from  the  funnel  and  spread 
out  on  a  glass  plate  or  the  concave  side  of  a  large  watch  glass. 
Now  with  a  wash  bottle  containing  hot  water  spirt  the  pre- 
cepitate  from  the  paper  into  the  beaker  in  which  the  precipi- 
tation was  made.  Add  moderately  strong  hot  nitric  acid  to 
the  paper  which  dissolves  the  remaining  stains  of  the  sulphide 
and  allow  to  run  in  beaker.  Finally,  wash  the  paper  with 
hot  water  until  it  has  no  acid  reaction.  (The  paper  is  now 
rejected. )  Boil  until  all  is  in  solution  and  only  the  light 
colored  sulphur  remains.  If  the  precipitate  is  dark  colored, 
due  to  undissolved  lead  sulphide,  add  a  few  c.c.  of  cone,  nitric 
acid  and  again  boil  which  will  usually  dissolve  the  last  traces 
of  the  sulphides.  Now  filter  and  wash  the  sulphur  until  free 
from  acid  and  if  filtrate  exceeds  50  C.G.,  boil  to  about  that 
volume  and  cool. 

Precipitate  lead  by  adding  cautiously  5  c.c.  cone,  sul- 
phuric acid  and  evaporate  as  rapidly  as  possible  without 
bumping.  When  the  dense  white  fumes  of  sulphuric  acid 
appear,  allow  to  cool.  Add  25  c.c.  water,  stir  to  dissolve  all 
zinc  sulphate,  then  stand  until  perfectly  clear  and  the  lead 
sulphate  is  settled.  Filter  in  a  Gooch  crucible,  wash  with  2% 
solution  of  sulphuric  acid  and  water,  until  all  sulphate  of  zinc 
is  washed  out,  then  remove  filtrate  and  finish  the  washing 
with  a  mixture  of  half  alcohol  and  half  water,  proceeding  as 
directed  on  p.  24  for  the  estimation  of  lead.  Multiply  the 


—  42  — 

lead  sulphate  by  .852  to  convert  to  2PbCO3PbH2O2.     (Basic 
carbonate  of  lead. ) 

Dilute  filtrate  to  about  400  c.c.,  heat  nearly  to  boiling, 
then  proceed  with  the  estimation  of  zinc  by  precipitating 
with  sodium  carbonate,  finally  igniting  and  weighing  as  zinc 
oxide  (Zn  O)  which  exists  as  such  in  the  sample.  Follow 
directions  for  estimation  of  zinc  on  p.  20. 

Filtrate  Containing  Calcium  Acetate  and  Magnesium 
Acetate. — Transfer  the  nitrate  to  a  beaker  and  rinse  out  the 
flask  which  contained  it  several  times  with  water,  adding  the 
washings  to  the  beaker,  and  boil  down  to  about  75  c.c.  If 
sulphuretted  hydrogen  is  not  entirely  disappeared,  continue 
boiling  until  but  a  very  faint  odor  is  perceptible.  Now  add 
ammonia  in  excess  and  to  the  hot  solution  add,  drop  by  drop, 
with  constant  stirring,  solution  of  ammonium  oxalate,  and 
allow  to  stand  on  the  edge  of  the  hot  plate  for  about  four 
hours.  Filter  the  calcium  oxalate,  washing  with  hot  water, 
dry,  ignite  and  weigh  as  calcium  sulphate,  calculating  to  cat- 
cium_carbonate  (CaCO3)  as  directed  on  p.  8. 

If  magneaiom  is  present,  evaporate  the  filtrate  to  about 
50  c.c.,  cool  and  proceed  as  directed  on  p.  9,  for  the  estima- 
tion of  magnesium.  Weight  of  magnesium  pyrophosphate 
(Mg2P2O7)  obtained  is  calculated  to  magnesium  carbonate 
(MgCO2)  by  multiplying  by  .7567. 

Note. — If  barium  carbonate  is  present  it  will  be  necessary  to  first 
separate  it  from  the  calcium  and  magnesium  by  adding  dilute  sulphuric 
acid  drop  by  drop  until  a  precipitate  ceases  to  form,  allow  to  stand  in  a 
warm  place  until  the  precipitate  is  pretty  well  settled,  then  filter  and 
proceed  as  in  barytes  for  the  washing  ignition  and  weighing  of  the 
barium  sulphate  (BaSOi).  Multiply  by  .845  to  convert  to  barium  car- 
bonate (BaCOs).  It  13  essential  that  the  solution  be  kept  quite  dilute 
and  a  few  c  c.  hydrochloric  acid  added  to  prevent  any  calcium  if  present 
from  precipitating  as  sulphate. 

Notes  on  Scheme  I. 

Note  I. — Owing  to  the  probable  presence  of  "sublimed 
lead"  or  products  containing  lead  oxide,  it  will  be  necessary, 
where  it  is  suspected,  to  make  an  estimation  of  the  carbonic 
acid  present,  which  may  be  done  by  the  apparatus  and 
method  described  on  p.  25.  Then  having  the  carbonic  acid 
(CO2)  calculate  it  to  basic  lead  carbonate  by  multiplying 
by  8.8.  Convert  the  basic  carbonate  of  lead  found  to  lead 


—  43  — 

sulphate  and  deduct  from  the  total  lead  sulphate  (acetic 
acid  solution),  and  if  there  is  any  excess  of  lead  sulphate 
(say  one  per  cent.)  it  is  calculated  to  lead  oxide  (PbO). 
Should  whiting  be  present  it  will  be  necessary  to  first  satisfy 
it  with  carbonic  acid  by  multiplying  the  calcium  sulphate 
(CaSO4)  found  by  .735  (of  if  CaO  by  1.885)  which  equals 
whiting  (CaCO3).  Now  find  the  carbonic  acid  (CO2)  in  the 
whiting  by  multiplying  by  .44,  and  deduct  from  the  total  car- 
bonic acid  found.  If  magnesium  carbonate  is  present,  cal- 
culate its  carbonic  acid  by  multiplying  by  .52  and  deduct  from 
the  CO2  left  Then  calculate  the  balance  of  the  CO2  to  basic 
carbonate  of  lead  by  factor  8.8.  Any  lead  left  unsatisfied  is 
calculated  to  lead  oxide  (PbO)  by  deducting  the  lead  in  the 
white  lead  from  the  total  lead  found  soluble  in  acetic  acid. 

Note  II. — If  the  sample  be  a  tinted  paint,  the  coloring 
or  tinting  pigment  is  usually  found  by  difference,  that  is,  the 
total  result  by  analysis  is  subtracted  from  100.  In  tinted  or 
mixed  paints  it  does  not  exceed  but  a  few  per  cent,  and  the 
pigment  used  in  coloring  is  disregarded. 

Note  III. — If  the  sample  consists  of  only  white  lead  and 
zinc  oxide,  dissolve  in  acetic  acid  as  usual,  filter,  and  instead 
of  precipitating  as  sulphides  the  lead  may  be  separated  at 
once  by  adding  sulphuric  acid  and  evaporating  as  usual,  and 
then  precipitating  the  zinc  in  the  filtrate.  The  lead  sulphate 
if  present  will  remain  insoluble  in  the  filter  and  is  treated  in 
the  usual  way.  As  lead  sulphate  is  not  absolutely  insoluble 
in  acetic  acid  particularly  when  it  is  present  in  large  amounts, 
it  is  well  to  make  a  determination  of  the  sulphuric  acid  and 
calculate  to  (PbSO4)  lead  sulphate,  then  deduct  from  the  total 
lead  sulphate  (both  soluble  and  insoluble  in  acetic  acid)  and 
the  balance  is  calculated  to  white  lead. 

Note  IV. — In  the  analysis  of  complicated  mixtures  of 
pigments  the  chemist  has  to  assume  some  arbitrary  formulae 
such  as  that  of  white  lead  which  do  not  always  conform  to 
the  theoretical  formula,  but  are  liable  to  vary  somewhat.  So, 
too,  in  the  estimation  of  china  clay.  Yet  there  is  no  ready 
method  that  will  give  these  in  their  exact  composition  and 
neither  is  it  necessary  in  the  analysis  of  a  paint  for  practical 
purposes. 


—  44  — 

3.     SCHEME  II. 

For  mixtures  containing  sulphates  or  carbonates  of  lead 
and  calcium  together  with  other  pigments. 

Carbonic  Acid. — If  carbonic  acid  is  present  it  is  esti- 
mated by  the  method  and  apparatus  as  described  on  p.  25. 

Sulphuric  Acid. — Determine  as  detailed  on  p.  21,  weigh- 
ing as  barium  sulphate,  convert  to  8O3  by  factor  .3433. 

Bases.— Boil  one  gram  20  minutes  with  about  40  c.c.  acid 
ammonium  acetate  sol  ution,  keeping  the  beaker  covered.  Filter 
and  wash  filter  thoroughly  with  hot  water. 


INSOLUBLE. 

Barytes,  china  clay,  silica  and 
magnesium  silicate.  Dry,  ignite 
and  weigh,  then  proceed  as  detail- 
ed for  the  separation  and  estima- 


FlI/TRATE. 

Lead,  zinc,  calcium  and  magne- 
sium acetates.  Proceed  as  detailed 
for  their  separation  and  estimation. 
Pages  41  and  42. 


tion  of  silica,  aluminum,  barium, 
calcium  and  magnesium,     p.  40. 

Notes  on  Scheme  II.  . 

Note  I. — If  the  qualitative  test  shows  that  lime  exists 
both  as  the  carbonate  and  sulphate  together  with  lead  sul- 
phate (and  the  latter  is  generally  present  in  mixed  paints), 
it  will  be  necessary  to  extract  and  estimate  the  lime  car- 
bonate, and  having  the  total  lime,  that  existing  as  sulphate 
may  be  calculated.  The  following  method  due  to  Thompson 
is  probably  the  best. 

Proceed  as  follows:  One  gram  of  the  sample  is  treated 
in  a  small  beaker  with  25  c.c.  of  a  mixture  of  1  part  nitric 
acid  (1.4)  and  9  parts  95  %  alcohol,  and  allowed  to  stand  without 
heating  for  20  minutes.  Then  decant  the  clear  liquid  on  a 
dry  filter  and  again  treat  with  the  alcohol-nitric  acid  mixture, 
allow  to  stand  and  filter  as  before,  repeating  the  operation 
four  times.  Finally  wash  the  paper  with  the  mixture.  The 
calcium  carbonate  together  with  some  lead  and  zinc  will  go 
into  solution,  while  any  gypsum  and  insoluble  matter  will 
remain  on  filter  and  is  disregarded.  Now  evaporate  the  fil- 
trate to  dryness  to  expel  alcohol,  and  add  sulphuric  acid  and 
heat  to  fumes.  Cool.  Add  a  few  c.c.  nitric  acid,  then  am- 
monia to  alkaline  reaction,  then  acetic  acid  in  excess,  and  boil 
to  solution.  While  hot  pass  sulphuretted  hydrogen  gas  until 


—  45  — 

saturated  and  filter  off  any  lead  or  zinc.  Wash  precipitate, 
first  by  decantation,  then  on  filter  with  water  containing 
hydrogen  sulphide,  and  evaporate  filtrate  and  washings  until 
sulphuretted  hydrogen  has  dissappeared.  Meke  alkaline 
with  ammonia  if  not  already  so,  precipitate  the  calcium  wit? 
ammonium  oxalate,  allow  to  stand  several  hours  in  a  warm 
place,  filter,  wash,  ignite  and  weigh  as  calcium  sulphate. 

Note  II. — As  basic  carbonate  of  lead  does  not  conform 
strictly  to  the  theoretical  formula  any  excess  of  lead  after 
satisfying  the  carbonic  acid  and  sulphuric  acid  does  not  nec- 
cessarily  imply  the  presence  of  lead  oxide.  The  latter  is 
usually  present  in  sublimed  products  or  in  the  presence  of 
much  lead  sulphate,  It  is  possible  that  a  very  small  percent- 
age of  lead  in  the  drier  may  not  have  been  completely  washed 
out  with  the  gasoline  or  ether,  but  this  is  the  exception 
rather  than  the  rule. 

Note  III. — Mention  is  made  of  the  presence  of  barium 
carbonate  but  it  is  little  used  in  American  paints.  Should  it 
be  found  with  soluble  sulphates  a  decomposition  will  take 
place  on  treatment  with  acid  forming  insoluble  barium  sul- 
phate and  complicating  !he  analysis.  Only  a  very  complete 
analysis  of  the  bases  and  acid  radicals  would  give  sufficient 
data  to  form  the  probable  combinations. 

A  paste  paint  has  recently  been  introduced  containing 
about  10  per  cent,  barytes  (blanc  fixe)  and  90  per  cent,  barium 
carbonate.  The  analysis  of  such  a  mixture  is  easily  made  by 
dissolving  in  dilute  hydrochloric  acid,  filtering  and  washing 
with  hot  water.  The  residue  after  ignition  and  weighing 
represents  the  barium  sulphate.  To  the  filtrate  dilute  sul- 
phuric acid  is  added  in  slight  excess  and  the  barium  sulphate 
obtained  in  the  usual  way  is  calculated  to  barium  carbonate 
by  the  factor  .845. 

Note  IV.—  Consult  notes  I,  II  and  III  in  Scheme  I. 

CALCULATIONS. 

When  Gypsum  is  Absent— If  no  gypsum  is  present,  cal- 
culate the  sulphuric  acid  (SO3)  to  lead  sulphate  by  factor 
a  7875,  and  deduct  from  the  total  lead  weighed  as  sulphate. 
Then  if  neither  whiting  or  magnesium  carbonate  is  present 
calculate  carbonic  acid  to  basic  carbonate  of  lead  by  factor  8.8 


—  46  — 

This  will  usually  satisfy  all  the  lead  and  is  checked  by  cal- 
culating the  basic  carbonate  of  lead  to  lead  sulphate  by 
factor  1.172,  and  substracting  the  result  from  the  total  lead 
sulphate.  From  the  remaining  lead  sulphate  deduct  that 
calculated  from  the  sulphuric  acid  and  should  any  yet  re- 
main it  is  figured  to  lead  oxide  (PbO)  by  using  factor  .735. 
(see  note  2).  If  whiting  and  magnesium  carbonate  are 
present  it  will  be  necessary  to  first  deduct  the  CO2,  combined 
with  them  by  multiplying  calcium  carbonate  by  factor  M 
and  magnesium  carbonate  by  factor  .52L 

When  Gypsum  is  Present. — If  gypsum  be  present,  cal- 
culate the  sulphuric  acid  (SO3)  in  it  by  factor  .564  and  deduct 
from  the  total  sulphuric  acid,  calculating  any  remaining 
to  lead  sulphate  by  factor  3.78.  Now  deduct  lead  sulphate 
from  total  lead  sulphate  and  the  remaining  lead  sulphate  is 
calculated  to  basic  carbonate  of  lead,  or,  if  no  carbonates  are 
present,  to  lead  oxide  (PbO).  If  carbonate  of  lime  and 
magnesium  are  present  deduct  the  carbonic  acid  contained 
in  them  before  combining  with  the  lead. 

The  calcium  extracted  by  the  nitric  acid-alcohol  treat- 
ment and  weighed  as  sulphate,  is  deducted  from  the  total 
calcium  found  and  the  difference  is  the  lime  existing  as 
gypsum.  As  it  is  usually  fully  hydrated  it  will  be  necessary 
to  calculate  the  calcium  sulphate  (CaSO4)  to  CaSO42H2O  by 
factor  1.26,  in  which  form  it  exists.  Zinc  is  weighed  as  oxide 
and  exists  as  such  in  the  sample. 


4.     *  Analyses  of  the  Solid  Portion  of  "Ready-Mixed" 
Paints.     (Light  Tints.) 

SSSg  :  :S2 

incjr-id    '•    *-OM 


ill 


*  By  the  Author. 


ill 


-  48  - 


5.     *  Analyses  of  "White  Paste  Paints. 

3 


S3£3  :  :$  :    g 


*  By  the  Author. 


•*  ^*CO     •     •  t»     •     •    I  i-( 

S  8  ^  •  • «  •  •  1 8 


APPENDIX. 


1.     Estimation  of  Turpentine,  Benzine  and  Water. 

A  majority  of  the  mixed  paints  contain  varying  amounts 
of  "turps,"  (turpentine)  or  benzine  or  water,  and  their  esti- 
mation is  attended  with  more  or  less  difficulty.  Owing  to  the 
proneness  of  "turps"  to  oxidize  when  exposed  to  the  air  any 
method  depending  on  its  distillation  and  condensation  is 
liable  to  give  results  too  low,  as  oxidation  products  are  formed. 
A  method  for  the  estimation  of  water,  "turps"  and  benzine 
has  been  proposed  by  Vernon  J.  Hall,  Ph.D.,  and  which  has 
given  excellent  results,  consists  in  mixing  the  sample  with 
lead  carbonate  (PbCO3)  (previously  dried  in  an  air  oven  at 
100°  C.,)  until  a  dry  powder  is  obtained,  and  then  distilling, 
using  a  special  condenser.  As  seen  in  the  cut  the  condenser 
has  an  inner  tube  through  which  the  neck  of  the  retort  passes, 
thus  enabling  the  latter  to  be  removed  at  the  end  of  the 
operation  if  it  becomes  necessary  to  apply  a  flame  to  drive 
down  any  drop  of  condensed  water  or  "turps"  that  frequently 
adhere  to  the  inner  tube  of  condensers. 

From  20  to  25  grams  of  the  thoroughly  mixed  sample 
are  quickly  weighed  out  in  a  small  beaker  and  the  beaker 
then  filled  with  the  carbonate  of  lead.  By  the  aid  of  a 
spatula  the  whole  is  now  mixed  and  chopped  into  fine  pow- 
der. If  it  appears  sticky  more  carbonate  of  lead  is  added 
and  a  sufficient  quantity  has  been  added  when  the  mixture  is 
a  dry  fine  powder.  It  is  now  transfered  to  the  retort  by  the 
aid  of  a  sheet  of  glazed  paper,  folded  funnel  shaped)  and  any 
dust  brushed  down  with  a  brush. 

The  graduate  H  is  also  weighed.  Connect  the  apparatus 
and  apply  at  first  a  low  flame  and  gradually  increase  the  heat 
until  a  temperature  of  about  120°  0.  is  obtained  which  will  be 
sufficient  to  volatilize  all  the  water  and  benzine.  Keep  at 
the  temperature  until  nothirg  more  comes  over.  Now  draw 


—  60  — 


the  retort  from  the  condenser  and  with  the  aid  of  the  flame 
drive  the  remaining  drops  down  into  the  graduate.  The  lat- 
ter with  its  contents  are  weighed,  and  the  increase  of  weight 


A  A   Retort. 

B   Condenser. 

CC   Inner  Tube  through  which 

neck  of  condenser  passes. 
D   Thermometer. 


Inlet  Water. 
Outlet  Water. 
Bunsen  Burner. 
Graduate  (1C  c.c. 
capacity;. 


equals  water  and  benzine.  If  water  is  present  it  will  be  the 
lower  layer  and  the  volume  of  each  is  noted.  Now  increase 
the  temperature  to  170°  C.,  at  which  point  all  "turps"  will 


-  51  — 


come  over.  When  distillation  ceases  again  remove  the  retort 
and  with  the  flame  drive  down  into  the  graduate  any  adhering 
drops.  Read  the  volume.  Any  increase  is  due  to  turpentine. 
Weigh  the  graduate  and  contents,  the  increase  in  weight  is 
total  water,  benzine  and  "turps."  The  percentages  are  found 


as  follows:    Suppose  25  grams  of  sample  were  taken  and  the 
distillate  weighed  2.1  grams,  then 

total  distillation. 


25        a4  per  centi  by 

Now  the  volumes  read,  benzine  1.2  G.C.,  water  L5  c.0.,  "turps" 
a3  c.c.,  total  aoo  c.c.,  then 

8.4xi.2_a36  per  ^^  benzine  by  weight 

Likewise,  we  would  find  4.2  per  cent  water  and  &4  per 
cent  "turps."    Deducting  this  total  distillate  11.2%  from  the 


—  52  — 

total  mixing  fluid  as  found  in  Chap.  L,  the  difference  is  the 
percentage  of  oil  by  weight 

A  method  has  been  proposed  by  H.  Joshua  Phillip, 
F.LC.,  F.C.S.  (Chemical  News,  Vol.  LXIII,  No.  1646,) 
which  consist  of  distilling  in  a  stream  of  coal  gas  thus  avoid- 
ing exposure  to  air.  As  shown  in  the  illustration  the  appara- 
tus consists  of  a  retort  A  into  which  is  fitted  a  three-way 
tube  B  by  means  of  a  tight  fitting  cork  In  the  tube  B  is 
a  thermometer  supported  by  a  cork  at  C  and  D  is  a  rubber 
tube  connecting  with  a  supply  of  coal  gas.  The  distillate  is 
collected  in  the  small  flask  F.  In  F  is  fitted  a  small  tube  G 
for  the  exit  of  the  coal  gas.  The  flask  F  is  allowed  to  rest  in 
a  basin  of  cold  water.  The  thoroughly  stirred  sample  is 
poured  into  a  small  beaker  and  quickly  weighed.  The  tube 
B  being  removed  the  sample  is  poured  into  the  flask  until 
the  beaker  is  quite  well  drained.  Now  weigh  again,  the 
difference  in  weight  being  the  amount  of  sample  taken. 
Connect  the  apparatus  and  start  slow  stream  coal  gas  and 
allow  to  run  for  some  time.  Then  light  at  G  and  regulate  so 
that  the  flame  will  be  about  three-  eigth  of  an  inch  in  length. 
Now  apply  heat  and  proceed  as  detailed  for  the  distillation 
and  estimation  of  "turps,"  benzine  and  water. 

Estimation  of  Oil  in  Flaxseed  and  Oil  Cake. 

The  best  solvent  for  extracting  the  oil  from  the  flaxseed 
and  cake  is  carbon  bisulphide  providing  it  can  be  obtained 
free  from  sulphur.  The  latter  may  be  detected  by  evaporat- 
ing a  portion  to  dryness  in  a  water  bath.  Should  sulphur  be 
present  which  is  invariably  the  case  it  may  be  removed  by 
carefully  distilling  off  the  carbon  bisulphide.  The  grade 
that  is  made  by  Schuchart  (Germany)  is  very  pure  and  con- 
tains such  a  slight  trace  that  it  need  not  be  taken  into  consid- 
eration. 

To  estimate  the  oil;  five  grams  of  the  oil  cake  are  used  or 
three  grams  of  ground  flaxseed  and  carefully  brushed  into  a 
four  ounce  Erlenmeyer  flask.  Then  add  about  25  c.c.  carbon 
bisulphide,  cork  loosely,  and  allow  to  stand  about  twelve 
hours  with  occasionally  a  gentle  agitation.  Pour  the  quite 
clear  carbon  bisulphide  in  a  filter  allowing  it  to  run  into  a 
weighed  beaker  of  about  200  c.c.  capacity.  Add  about  15  c.c. 


—  53  — 

more  bisulphide  to  the  residue  agitate  gently  and  allow  to 
stand  about  15  minutes  or  until  the  sample  is  pretty  well 
settled,  again  pour  off  and  repeat  the  treatment  about  four 
times.  Then  with  the  aid  of  a  wash  bottle  containing  carbon 
bisulphide  wash  the  remaining  seed  or  meal  to  the  filter, 
finish  the  washing  of  the  beaker  allowing  the  bisulphide  to 
run  on  the  filter  and  thoroughly  wash  the  oil  from  the  paper. 
When  the  carbon  bisulphide  is  all  run  through  place  the 
beaker  and  contents  in  a  warm  place  until  the  carbon  bisul- 
phide is  evaporated  then  heat  in  an  air  oven  at  a  temperature 
of  110°  C.  for  about  15  minutes.  Cool  and  weigh.  The 
increase  of  weight  equals  the  oil  which  multiplied  by  100  and 
divided  by  the  weight  of  sample  taken  gives  the  percentaga 


—  54  — 

2.     List  of  the  Principal  Pigments  with  Chemical 
Formula  and  Trade  Names. 

WHITE  PIGMENTS. 
Chemical  Name.  Formula.  Trade  Name. 

Sulphate  of  Barium . . .  BaSOi Barytes,  "Blanc  Fixe." 

Carbonate  of  Calcium. CaCO3 Whiting,  Lime  Carbonate 

Lime,  Paris  White,  En- 
glish White,  Spanish 
White,  Marble  Dust. 

Sulphate  of  Calcium . .  CaSO42H2O Gypsum,  Terra  Alba, 

Plaster  of  Paris  (CaSO4 
2H2O,  when  dehydrated.) 

Sulphate  of  Strotium . .  SrSO4 Strontian  White. 

Sulphate  of  Lead PbSO4 Sublimed  Lead,  "White" 

Lead. 

Silica SiO2 Silex,  Silver  White,  Wood 

Filler,  Infusorial  Earth, 
Ground  Quartz. 

Oxide  of  Zinc ZnO Zinc  White,  Zinc  Oxide, 

Zinc. 

Hydrated  Silicate  of  2  SiO2Al2032H2O China  Clay,  Clay. 

Alumina. 

Carbonate  of  Magn'm .  MgCO3 Magnesite. 

Silicate  of  Magnesium .  46#  to  58#  SiO2 Talc,  Soapstone,  French 

29#  "  34#  MgO Talc,  Steatite. 

02#  «  07#H,0 

(with  small  amounts  Iron 
Oxide  and  Alumina.) 

Sulphide  of  Zinc ZnS Mixed  with  Barytes  and 

Zinc  Oxide  is  "Lithopbone." 
Basic  Carb'te  of  Lead.2PbCO3PbH2O2 White  L'd,  Corroded  L'd. 

GREENS. 

Pure  Chrome  Green . . .  Cr2O3 Chrome  Greens. 

Chrome  Green PbCrO4 Chrome  Greens 

PbSO4 

2PbCO3+PbH2O2 

K2Fe22Fe(CN)6 

Chrome  Green K2Fe2(FeCN)2 BrunswickGreen. 

PbCrO4 

PbSO4 

BaSO4 

"Scheele's"  Green CuAsO3CuO2H2O 

"Emerald"  Green 7Cu2C2H3Oo3CuAs2O4 . 


—  55  — 

BLUES. 
Chemical  Name.  Formula.  Trade  Name. 

Ultramarine Composition  by  Gmelin 

SiO, 47.306 

A12O3 22-000 

Na2O 12.063 

S 0.188 

CaCOs 

CaO 1.5:16 

H2SO4 4.679 

Water,  etc...  12.218 

Prussian  Blue Potassium  Ferric  Ferro-     Berlin  Blue,  Chinese 

cyanide    K2Fe22Fe(CN)6        Blue. 
REDS. 

Lead  Monoxide PbO Litharge,  Lead  Oxide, 

Massicot. 

Lead  Oxide PbsO4 Red  Lead,  Orange  Red. 

Basic  Chromate  of  L'd .  PbCrO4-f-PbO Dark  or  Basic  Chromate 

of  Lead,  Chrome  Red, 
Scarlet  Lead,  Derby  Red. 

Sulphide  of  Mercury . .  HgS Mercury  Vermilion,  Chi- 
nese Vermilion. 

Red  Lead  or  Orange  Mineral Artificial  Vermilion,  Am- 

Barytes  as  a  base  tinted  erican  Vermilion,  Ver- 

with  eosine  (aniline).  milionettes,  Aniline 

Reds,  Royal  Reds. 

Oxide  of  Iron FejOs Indian  Reds,  Rouge,Vene- 

tian  Red,  Princes  Mineral, 
Tuscan  Red. 

Carbonate  of  Iron FeCOs Crocus. 

YELLOW  AND  ORANGE. 

Chromate  of  Lead PbCrO4+PbSO4 Chrome  Yellow,  Chrome, 

(Sometimes  white  lead)        Lemon  Chrome. 

Chromate  of  Lead PbCrO4 Orange  Chrome. 

Ochres  and  Siennas:— Silicate  of  alumina  colored  by  hydrated  ferric  oxide 
in  ochres  and  hydrated  ferric  oxide  with  manganese  oxide  in  Siennas. 
BLACK  PIGMENTS. 

Carbon C Lamp  Black,  Gas  Black. 

Carbon,  with  Phos-      60#  Phosphate  of  ....  Ivory  Black,  Bone  Black, 
phate  of  Calcium.          Calcium.     15$  Car-        Drop  Black,  Animal 
bonate  of  Calcium         Black, 
and  some  silica,  iron 
and  alumina.     25$ 
Carbon 

Graphite C Graphite. 

BROWN  PIGMENTS. 

Umber,  both  raw  and  "burnt,"  is  the  chief  brown  pigment.  Essentially 
ochres  or  siennas  but  contain  more  manganese,  the  latter  varying  from 
7  to  12  per  cent.  MnO2. 


-  56  - 


3.     Atomic  Weights. 


Name. 
Aluminium.. 
Antimony  .  .  . 
Arsenic  

Sym- 
bol. 
.  Al 
..Sb 
..As 

Quanti- 
valence. 

IV 
V 

v 

Atomic 
Weight. 

27.0 
120.0 
74.9 

Name. 
Mercury  
Molybdenum  . 
Nickel  

Sym- 
bol. 
•Hg 
.Mo 

Ni 

Quanti- 
valence. 
II 
VI 
VI 

Atomic 
Weight. 

200.0 
96.0 
590 

Barium  

..B» 

II 

136.80 

Nitrogen  

N 

v 

14.0 

Bismuth 

Bi 

v 

2100 

Os 

IV 

1990 

Boron.   . 

B 

III 

11.0 

Oxvcen 

o 

II 

160 

Bromine.  . 

.  Br 

I 

80.0 

Palladium 

Pd 

IV 

1060 

Cadmium  .  .  . 
Caesium  

..Cd 
..Cs 

II 
I 

112.0 
133.0 

Phosphorus  .  . 
Platinum  

.P 
Pt 

V 
IV 

31.0 
197.0 

Calcium  .... 

..Ca 

II 

40.0 

Potassium.  .  .  . 

K 

I 

39.1 

Carbon  
Cerium  
Chlorine  

..C 
..Ce 

..Cl 

IV 

III 

I 

12.0 
141.2 
35.5 

Rhodium  
Rubidium  
Ruthenium. 

.Ro 
.Rb 
"Rn 

IV 

I 

IV 

104.0 
85.0 
104.0 

Chromium.  .  . 
Cobalt  

..Cr 
..Co 

VI 
VI 

52.4 
59.0 

Selenium  
Silicon  

.Se 

Ri 

II 

IV 

79.0 
28.0 

Columbium 

Cb 

v 

94.0 

Silver 

Ae 

I 

1080 

Copper. 

Cu 

II 

63.1 

Sodium 

Ni 

I 

23.0 

Didymium  .. 
Erbium  

..D 

.  .E 

III 
III 

147.0 
169.0 

Strontium  .  .  . 
Sulphur  

.Sr 
B 

II 

II 

87.5 
32.0 

Fluorine 
Gallium 

..P 
Ga 

I 

III 

19.0 
699 

Tantalum 
Tellurium 

.Ta 
Te 

V 
II 

182.0 
128.0 

Glucinum... 
Gold  

..Gl 
..Au 

II 

III 

9.2 
196.2 

Thallium  
Thorium  

.Tl 
Th 

I 

IV 

204.0 
231.5 

Hydrogen  .  .  . 

.  .H 

I 

1.0 

Tin  

Sn 

IV 

118.0 

Indium  
Iodine 

..In 
I 

III 

I 

113.4 

12685 

Titanium  
Tungsten. 

.Ti 
W 

IV 
IV-VI 

50.0 
1840 

Iron 

Fe 

VI 

56.0 

Uranium 

TT 

VI 

2400 

Lanthanum. 
L«ad  

..La 
.  Pb 

III 

II 

139.0 
207.0 

Vanadium  ... 
Yttrium  .... 

.V 
Y 

v 

III 

5L2 
60.0 

Lithium  

..Li 

I 

7.0 

Zinc  

7,n 

II 

65.0 

Magnesium.  . 
Manganese  .  . 

..Mg 
..Mn 

II 

VI 

24.0 
55.0 

Zirconium  .  .  . 

.Zr 

IV 

90.0 

4.     Measures  and  Weights. 

MEASURES  OF  CAPACITY, 


Grains  of 
Water 

Cubic 
Ceuti- 

Gals          Qts.           Pts.             Fl.  Oz.       FL  Dr.               at62°F. 

metres. 

1=4     =     8     =     128    =    1,024    =    58,318.00    = 

3,785,200 

1      =     2=       32=       256    =    14,579.50    = 

946,300 

1      =       16    =       128    =      7,289.75    = 

473,150 

1    =          8    =        455.61    = 

29,570 

1    =          56.98    = 

3,690 

1 

English  imperial  gallon  =  277.274  cu.  in.    =    70,000.00    = 

4,543,000 

1 

"        wine  or  Win- 

1 
1 

chester  gal.    =  231.000       "        =    58,318.00    = 
"        corn  gallon        =  268.000       "        =    67,861.00    = 
ale        "             =  282.000       "        =    71,193.40    = 

3,785,200 
4,402,900 
4,619,200 

1              cu.  ft.    =    283.15  cc. 

1             cu.  in.    =      16.38   " 

0.061027       "        =            1   " 

LINEAR  MEASURES. 

1  yd    =    3  ft.    =    36  in.    =    0.91438  metre. 

1ft.    =    12  in.    =    0.30480      " 

lin.    =    0.02540      " 

39.3708  in.    =    1.00000      " 

TBOY  WEIGHT. 

lib.    =    12  oz.    =    240    cwt.    —    5,760  grs.    =    373.2419 

grammes. 

1   «     =      20      ••        —       480    "       =      31.1035 

»« 

1      «        =        24    "       =        1.5552 

<« 

1    "       =       0.0648 

«« 

AvoiRDUPoib  WEIGHT. 

1  greas  ton    =    20  cwt.    ==    2,240  Ibs.    =    1,016.00  kilogrammes. 
1    «       =       112  "        =         50.80 


Oz. 

lib.    =    16 
1 

1  net  ton  =  2,000  Ibs.  = 
1  cu.  ft.  of  water  at  62°  F.  = 
1  cu. in. "  "  "  "  = 


Grs.  Troy.  Grammes. 
=  7,000.00  =  453.5926 
=  437.50  =  28.3495 

907  kilogrammes. 

62.3550  Ibs.  Av.    =   28315.0000  grammes. 
0.0361    "     "       =         16^862 


APOTHECARIES  WEIGHT. 

1  Ib.  =  12  oz.  =  96  dr.  =  288  scruples  =  5,760  grains  =  373.2419  grams. 

1   "   =    8  "   =    24  480  31.1035      " 

1  «   =     3  60  3.8879      " 

1  20  1.2960      " 

0.0022  Ib.  Av.    —    0.03527  oz.  Av.    =    15.4328     =     1.0000      " 


..INDEX., 


Aluminum,  in  China  Clay 11 

American  Vermilion 55 

Ammonium  Acetate  Solution.  .33 

Aniline  Red 55 

Animal  Black 55 

Analyses,   table  of  white  and 

tinted  "Mixed  Paints" 47 

Analyses,  table  of  white  "Paste 

Paints" 48 

Analysis  of  Barytes,  16;  Cal- 
cium Carbonate,  7;  China 
Clay,  15;  Gypsum,  15;  Magne- 
site,  17;  Magnesium  Silicate, 
18;  Silica,  15;  White  Lead,  24; 

Zinc  Oxide 19 

Apparatus    for    estimation    of 

carbonic  acid  in  white  lead. . .  27 
Apparatus    for    estimation    of 
Turpentine,      Benzine      and 

Water 50 

Apparatus  for  white  lead  an- 
alysis  29 

Appendix 49 

Arbitrary  Formulae 43 

Artificial  Vermilion 55 

Atomic  Weights,  table  of 56 

Basic  Carbonate  of  Lead 24-54 

Basic  Chromate  of  Lead 55 

Barium  Carbonate  and  Barium 

Sulphate,  analysis  of 45 

Barium  Carbonate,  estimation 

of  in  pain.ts 42 

Barium  Sulphate,  analysis  of..  16 

Barytes 16-54 

Barytes,      estimation      of     in 

paints 40 

Barytes,  qualitative  tests  for.  .17 
Benzine,      estimation      of      in 

paints 49 

Black  Pigments 55 

Blanc  Fixe  ..  ...16-54 


PACK 

Blank  Tests 2 

Blues 55 

Bone  Black 55 

Brown  Pigments 55 

Brunswick  Green 54 

Calcium  Carbonate,  7;  in  whit- 
ing, 8;  estimation  of,  in 

paints 42 

Calcium  in  china  clay 14 

Calcium  Sulphate  in  whiting. .  9 
Carbon  Bisulphide,  for  extrac- 
tion of  oil  in  flaxseed 52 

Carbonic  Acid,  estimation  of  in 

white  leads 25 

Centrifugal  Machine,  for  sepa- 
ration of  oil  and  pigments. . .  5 

China  Clay 54 

China  Clay,  analysis  of,  15;  an- 
alysis of,  11;  composition  of, 
10;  estimation  of,  in  paints.  .40 

Chinese  Vermilion 55 

Chrome 55 

Chrome  Greens 54 

Chrome  Red, 55 

Chrome  Yellow 55 

Clay 54 

Coloring  Pigment 43 

Combustion  Method  for  white 

lead 28 

Corroded  Lead 54 

Crocus 55 

Derby  Red 55 

Drop  Black 55 

English  White 54 

Ferrous  Sulphate,  for  standar- 
dizing potassium  perman- 

gate  solution 13 

Filtering  Apparatus 37 

French  Talc 54 

Fresenius,  study  of 1 

Gas  Black...  ...55 


PAGE 

General  Precautions 1 

Gooch  Crucible  and  Cone 2 

Gooch  Crucible,  to  prepare  for 

use 36 

Graphite 55 

Green  Pigments,  list  of 54 

Gypsum,  54;  analysis  of,  10;  Cal- 
culations when  present  in 
complicated  mixture,  46; 

qualitative  test  for 33 

Hall,  Vernon,  J.,  method  of. .  .49 

Indian  Reds 55 

Infusorial  earth 54 

Insoluble  matter  in  zinc  pig- 
ments   23 

Insoluble  residue  in  paints. . .  .40 

Iron  in  China  clay 11 

Iron  and  Alumina  in  whiting. .  8 
Iron,  separation  from  alumina. 12 

Ivory  Black 55 

Kaolin   10 

Lamp  Black 55 

"Leaded  Zinc,"  mention  of.    .  .31 
Lead    in    white   lead,  estima- 
tion of 24 

Lead  in  zinc  oxide,  estima- 
tion of 19 

Lead  Oxide  in  paints 46 

Lead   Sulphate,   estimation   of 

in  mixtures 39 

Lead  Sulphite 34 

Lemon  Chrome 55 

Lame  Carbonate 54 

Linseed  Oil,  estimation  of  in 

flax  seed  and  oil  cake 52 

Litharge 55 

Lithophone 54 

Magnesite 17-54 

Magnesium  Carbonate,  analy- 
sis of,  17;  estimation  of,  in 
paints,  42;  in  whiting,  9;  in 

china  clay 14 

Magnesium  Silicate,  composi- 
tion of,  18;  estimation  of,  in 
paints 41 


PAGE 

Marble  Bust 54 

Massicot 55 

Measures  and  Weights 56-57 

Mercury  Vermilion 55 

Mixing  Fluid 3 

Oil,  percentage  of,  in  paints,  4; 
separation,  by  centrifugal 
machine,  5;  oil,  separation 
from  sample,  3;  separation, 

with  nitric  acid 6 

Ochres 55, 

Orange  Chrome 55 

Orange  Lead 55 

Paper,  filter 2 

Paris  White 54 

Pigments,   list  with   chemical 

formula  and  trade  names 54 

Phillips,  H.  J.,  method  for  dis- 
tillation of  turpentine,  ben- 
zine and  water 52 

Plaster  of  Paris 10-54 

Potassium  permanganate  solu- 
tion  13 

Potassium,      separation     from 

sodium,  in  china  clay 14 

Princes  Mineral 55 

Prussian  Blue 55 

Quantitative  analysis,  scheme 

to  use 35 

Quanti valence,  table  of 56 

Qualitative  tests,  of  white  and 

tinted  paints 32 

Quartz,  ground 54 

Reagents,  purity  of 1 

Red  Lead 55 

Rouge 55 

Royal  Red 55 

Samples,  preparation  for  an- 
alysis  3 

Scarlet  Red 55 

Scheme  to  use,  in  quantitative 

analysis 35 

Siennas .55 


PAGE 

Silex 15-54 

Silica,  15;  estimation  of,  in 
paints,  40;  in  china  clay,  11; 

in  whiting 7 

Silver  White 54 

Soap  stone 18-54 

Sodium,  separation  from  po- 
tassium in  china  clay 14 

Solvents,  for  extraction  of  oil..  3 

Soxhlet  extractor,  for  oils 4 

Spanish  White 54 

Steatite 18-54 

Strontian  White 54 

Sublimed  Lead 54 

Sublimed    Lead>     Calculations 

when  present 42 

Sulphate  of  Calcium. 10 

Sulphate   of    Zinc,    estimation 

of 22 

Sulphuric  acid,  estimation  of  in 

zinc  oxide  or  paints 21 

Table    of    Analyses   of    ready 

mixed  paints 47 

Table    of    Analyses    of    white 

paste  paints 48 

Talc 18-54 

Terra  Alba 10-54 

Testing  for  Barytes 17 

Thomson,  method  for  the  esti- 
mation of  calcium  carbonate, 
gypsum,  lead  sulphate,  etc. .  .44 


PAGB 

Turpentine,   estimation   of,  in 

paints 49 

Tuscan  Red 55 

Ultramarine 55 

Umber 55 

Venetian  Red 55 

Vermilionettes ,   55 

Vermilions 55 

Water,  distilled _  2 

Water,  estimation  of,  in  paints, 
49;  in  china  clay,  15;  in  gyp- 
sum    10 

Weights,  table  of 56 

White  Lead,  54;  analysis  of,  24; 

composition  of  ..,...<...   . , .  24 
White  Lead,  estimation  of  in 

paints 41 

White  Pigments 7 

Whiting,  54;  analysis  of 7 

Wood  Fillers 54 

Zinc,  54;  metallic,  for  standar- 
dizing potassium  permanga- 
nate solution 13 

Zinc  Oxide,  analysis  of,  19;  esti- 
mation of,  in  paints 41 

"  Zinc-Lead,"  mention  of 31 

Zinc  Pigments,  analysis  of. . .  .23 
Zinc    Sulphide,  for  white  pig- 
ments   54 

Zinc  Sulphite,  mention  of 34 

Zinc  White ,...54 


ESTABLISHED  J760 


FACTORIES:  London,  Sheffield,  New  York 
'BRANCHES;  Chicago,  Paris,  Bombay,  Vienna,  Sydney,  Etc. 


L&wis  Berger  8  Sons 

...LIMITED... 
Manufacturers  and  Importers  of  all 

FINE  DRY  COLORS 

SPECIALTIES  FOR  GRINDERS 


PRUSSIAN  AND  CHINESE  BLUES. 

Unexcelled  for  Strength,  Tone,  Purity. 

ENGLISH  QUICKSILVER  VERMILION. 

Berber's  World  Renowned  Brand. 

PERMANENT  REDS, 

Every  Description. 

UMBERS,  SIENNAS,  OXIDES,  OCHRES, 

Double  Strength  for  Tinting. 


Samples  of  colors  sent  us  will  be  carefully  examined,  and  a  report  as 
to  strength,  durability  and  value,  promptly  rendered. 


NEW  YORK  OFFICES:  CHICAGO  BRANCH: 

248  Front  Street.  84  La  Salle  Street. 

WORKS:  Elizabethport,  N.  J.,  U.  S.  A. 


Yhone  120  SM&in 


GEORGE  K  ELLIS 

TECHNICAL 
CHEMIST 


SPECIALTY:    PAINTS,  PIGMENTS,  OILS,  ETC 

Contracts  made  for  yearly  work. 
Special  prices  for  series  of  analyses. 


LABORATORY  AND  OFFICE 

J63  Randolph  Street,  Cor.  LaSalle 
CHICAGO 


"  Send  for  Analysis  of  Mound  City 
Paint  and  Color  Company's  Strictly  Pure 
Horseshoe  Brand  of  Ready  Mixed  Paint. 
Absolutely  Pore*  We  stand  in  no  fear 
of  analytical  examination." 

MOUND  CITY  PAINT  &  COLOR  CO. 
St.  Louis  Missouri. 


A  Journal  Devoted  to  Paints,  Petroleum  PUBLISHED  EVERY  WEDNESDAY. 

and  OtheK^Giaw,  Drugs,  Two  DOLLARS  A  YEAR. 


Paint,  Oil  and  'Drag 


D.  VAN  NESS  PERSON,  Publisher 

84  and  86  LA  SALLE  STREET 
CHICAGO 


The  Reliable  Medium  for  Manufacturers, 
Jobbers  and  Dealers 


T.  L.  BLOOD  &  CO, 


MANUFACTURERS  OF 
HIGH  GRADE 


PAINTS 


OF  EVERY  DESCRIPTION 


St.  Paul,  Minnesota. 


E.  H.  SARGENT  &  CO. 


. . .  ESTABLISHED  J852 . . . 


Special  Catalogues 

^Apparatus  for  .                                              and 

Taint  and  Color  l^lj|gs!s^f '               Trices  upon 

Determinations  ^B                               111         (Application 


IMPORTERS  AND  'DEALERS  IN 

Chemicals .... 
and  Chemical  Apparatus 

...FOR... 

Analytical  Laboratories 

Microscopes,  and  other  Instruments  for 
Scientific  Investigations. 

106-108  Wabash  Avenue,      -      -      CHICAGO. 


Established  1832.  Incorporated  1882. 


Valentine  &  Company 


HENRY  C.   VALENTINE,   PRESIDE 


^Manufacturers  of 
High  Grade... 


Coach  and  Railway  Varnishes 
and  Colors 


NEW  YORK, 

57  Broadway. 


BRANCH  HOUSES: 


CHICAGO,  BOSTON, 

390  Wabash  Avenue.  J64  Purchase  Street. 

PARIS, 
2*  Rue  de  Lappe. 


Our  VARNISHES,   GROUND  ROUGHSTUFF  and  COACH- 
PAINTERS'  COLORS  are  kept  in  stock,  and  are 
for    sale    in  the  United    States    by    the 
Leading  Dealers  in  Paints    and 
Carriage-Makers'  Supplies. 


<Pa»rf 


c/lbsolutely 


Sold 
Subject 
to  Chemical 
Analysis^ 


of  wonderful  covering  capacity.  Of 
greatest  durability.  That  looks  the 
best.  That  costs  less  in  the  end  ... 


We  Guarantee  the  cMonarch  cMixed 


Is  it  not  safer  to  pay  the  price  of  a  good  article  and  be  satisfied,  than  to  run 
the  chances  with  cheap  goods?  Painting-  is  too  expensive,  and  the  work  too 
important  to  risk  results.  The  experience  of  those  who  practice  economy  is,  that 
it  pays  to  use  the  best. 

Monarch  Paint  has  been  before  the  public  for  fifteen  years,  and  enjoys  an 
enormous  trade  from  New  England  to  the  Pacific  Coast.  Wherever  tried,  Monarch 
has  proved  to  be  what  is  claimed  for  it— a  heavy  bodied  Lead,  Zinc  and  Oil  Paint; 
absolutely  pure  materials  only,  and  those  of  the  best  quality  being  used  in  its  manu- 
facture. Color  card  on  application. 

SENOUR  MANUFACTURING  CO. 

Pioneers  of  Tare  Taints. 


PRICE  LIST 

..OF... 


V 

ralentines  Coach  Varnishes 


FINISHING  SSSr&il 

earing- Body  Varnish $6.00 

edium  Drying  Body  Varnish 6.00 

Elastic  Gear  Varnish 5.00 

One  Coat  Coach  Varnish 4.50 

One  Coat  Gear  Varnish...  ..3.50 


RUBBING 

Hard  Drying-  Body  Varnish  (4-day  rubbing-) 5.00 

Quick  Leveling-  Varnish  (2-day  rubbing-) 4.00 

Flatting  Varnish 3.00 

Black  Japan 4.50 

Black  Color-and- Varnish...  ..4.00 


MISCELLANEOUS 

No.  1  Black  Varnish 1.50 

Carriage  Top  Dressing 4.00 

Quick  Black  Lacquer 4.00 

Japan  Gold  Size 3.50 

Crown  Coach  Japan 1.75 

Dark  Permanent  Wood  Filling 4.00 

Light  Permanent  Wood  Filling 4.00 


ORGANIZED  INCORPORATED 

1868.  1883. 

IN   BUSINESS  31   YEARS. 


We  sold  the  first  bill  of  READY  MIXED 
PAINT  in  Chicago  May  12,  1868,  and  are  still 
in  the  business. 

We  are  now  building  a  new  thoroughly 
equipped  factory,  corner  of  Fulton  and  Car- 
penter Streets,  where  our  facilities  for  manu- 
facture will  be  unsurpassed. 

Our  Paints  speak  for  themselves.  We 
prefer  the  opinions  of  customers  to  statements 
of  our  own. 


Geo.  W.  Pitkin  Co. 

CHICAGO. 
MAKERS  OF  PAINTS  AND  COLORS 


The  La<wson  Varnish  Co/s 

DESCRIPTIVE  PRICE  LIST 

OF 

High  Grade  Varnishes 
For  House  ^Painters  and  Decorators 


INSIDE  LUSTRO, 

For  the  finish  and  preservation  of  all  hard  wood-work 
in  house  and  public  buildings. 

OUTSIDE  LUSTRO, 3.50 

For  use  on  front  doors,  vestibules,  window-casings, 
store-fronts,  signs,  etc. 

ELASTIC  FLOOR,       -------         2.50 

For  finishing  and  preserving  hard  wood  floors.   Its  use 
enables  them  to  be  kept  clean  with  the  least  labor. 

PALE  RUBBING, 3.00 

A  nearly  colorless  varnish  for  interior  decoration— es- 
pecially adapted  for  use  on  White  Enamel  work. 

EXTRA  HARD  OIL  FINISH, 2.00 

For  interior  finishing  of  natural  woods.    Good  body, 
dries  quickly  and  hard,  with  good  luster. 


302  Wabash  Avenue,  J68  Purchase  Street, 

CHICAGO.  BOSTON. 

57  Broadway,  New  York. 
FACTORY:  Chicago. 


UNIVERSITY  OF  CALIFORNIA  AT  L.OS  ANGI 
THE  UNIVERSITY  LIBRARY 


This  book  is  DUE  on  the  last  date  stamped  below 


MAY  2  5  1848 
JUL9      1947 

*L> 
MAR  6     1953 


UN  1; 

AUG 
JAN  2  2  196Z 

REC'D 


IIEC'D  ID-UN. 


n« 


UNIVERSITY  of  CALIFORNIA 

AT 

LOS  ANGKLES 
LIBRARY 


,^,?,°^RN  REGIONAL  LIBRARY>ACILITY 


AA    001  034  903    3 


